I am not a bible teacher, but I will give it a go. First of all, Wikipedia Article on Usury. I notice that you quoted the passage from the King James version. I would say the definition of the word, "usury" has changed over the course of 500 years. I also did not read the 1545 Act referenced in the Wikipedia article. (I have no idea if the King James use of the word "usury" condemns the action like today's use of the word "usury" would.)
(I generally see the condemnation against usury as against rich people taking advantage of poor people.)
The issue in question is the Master gave the Servant a job: Here is $20K. Go an invest it. Did he double his money like the other two servants? No. Was he supposed to invest it? Yes. Was he afraid of his boss? Yes. Clearly, as you said. Now he has to give an account of the money right after the other two did well and doubled their money.
Did the servant have any right whatsoever to pass judgment on his master like that? No. He had a job to do, but he did not do it and now he was trying to justify himself by condemning his boss's actions.
What does Old Testament law say about Usury? It is written in the Wikipedia article. One verse says you may lend to a foreigner with interest.
This might be similar to how you might feel about loaning money to close friends and family members. You might not charge them interest, but you will expect your money back. However, if you were loaning money to a stranger, you are much more likely to draw up a document stating the exact details of the loan, including the interest rate.
What is the context of the prohibition against usury?
I do not know anything about ancient Jewish society. Is a rich person loaning money to a poor person expecting nothing in return simply to be generous? I wonder how the rich person profits? Simply from being generous? If the poor person profits from the rich person's generosity, did the poor person traditionally give something on top of the repayment? I don't know. I'm just asking.
If I lent you $100 to go play blackjack or something, I am really expecting to see substantially less money back, if anything at all. However if you have a great night playing and you have $200, you will certainly return the $100. You might even return something on top of it.
Long post. Does any of this make sense?
I always thought that historically, Christians considered charging any amount of interest to be usury.
https://www.theobjectivestandard.com/issues/2007-fall/morality-of-moneylending/
Spoiler :
During the Dark Ages, the concept of an economy had little meaning. Human society had reverted to a precivilized state, and the primary means of trade was barter. Money all but disappeared from European commerce for centuries. There was, of course, some trade and some lending, but most loans were made with goods, and the interest was charged in goods. These barter-based loans, primitive though they were, enabled people to survive the tough times that were inevitable in an agrarian society.6
Yet the church violently opposed even such subsistence-level lending.
During this period, the Bible was considered the basic source of knowledge and thus the final word on all matters of importance. For every substantive question and problem, scholars consulted scripture for answers—and the Bible clearly opposed usury. In the Old Testament, God says to the Jews: “[He that] Hath given forth upon usury, and hath taken increase: shall he then live? he shall not live . . . he shall surely die; his blood shall be upon him.”7 And:

In one breath, God forbade usury outright; in another, He forbade the Jews to engage in usury with other Jews but permitted them to make loans at interest to non-Jews.
Although the New Testament does not condemn usury explicitly, it makes clear that one’s moral duty is to help those in need, and thus to give to others one’s own money or goods without the expectation of anything in return—neither interest nor principal. As Luke plainly states, “lend, hoping for nothing again.”9 Jesus’ expulsion of the moneychangers from the temple is precisely a parable conveying the Christian notion that profit is evil, particularly profit generated by moneylending. Christian morality, the morality of divinely mandated altruism, expounds the virtue of self-sacrifice on behalf of the poor and the weak; it condemns self-interested actions, such as profiting—especially profiting from a seemingly exploitative and unproductive activity such as usury.
Thus, on scriptural and moral grounds, Christianity opposed usury from the beginning. And it constantly reinforced its opposition with legal restrictions. In 325 a.d., the Council of Nicaea banned the practice among clerics. Under Charlemagne (768–814 a.d.), the Church extended the prohibition to laymen, defining usury simply as a transaction where more is asked than is given.10 In 1139, the second Lateran Council in Rome denounced usury as a form of theft, and required restitution from those who practiced it. In the 12th and 13th centuries, strategies that concealed usury were also condemned. The Council of Vienne in 1311 declared that any person who dared claim that there was no sin in the practice of usury be punished as a heretic.
There was, however, a loophole among all these pronouncements: the Bible’s double standard on usury. As we saw earlier, read one way, the Bible permits Jews to lend to non-Jews. This reading had positive consequences. For lengthy periods during the Dark and Middle Ages, both Church and civil authorities allowed Jews to practice usury. Many princes, who required substantial loans in order to pay bills and wage wars, allowed Jewish usurers in their states. Thus, European Jews, who had been barred from most professions and from ownership of land, found moneylending to be a profitable, albeit hazardous, profession.
Although Jews were legally permitted to lend to Christians—and although Christians saw some practical need to borrow from them and chose to do so—Christians resented this relationship. Jews appeared to be making money on the backs of Christians while engaging in an activity biblically prohibited to Christians on punishment of eternal damnation. Christians, accordingly, held these Jewish usurers in contempt. (Important roots of anti-Semitism lie in this biblically structured relationship.)
Opposition to Jewish usurers was often violent. In 1190, the Jews of York were massacred in an attack planned by members of the nobility who owed money to the Jews and sought to absolve the debt through violence.11 During this and many other attacks on Jewish communities, accounting records were destroyed and Jews were murdered. As European historian Joseph Patrick Byrne reports:

In 1290, largely as a result of antagonism generated from their moneylending, King Edward I expelled the Jews from England, and they would not return en masse until the 17th century.
From the Christian perspective, there were clearly problems with the biblical pronouncements on usury. How could it be that Jews were prohibited from lending to other Jews but were allowed to lend to Christians and other non-Jews? And how could it be that God permitted Jews to benefit from this practice but prohibited Christians from doing so? These questions perplexed the thinkers of the day. St. Jerome’s (ca. 347–420) “solution” to the conundrum was that it was wrong to charge interest to one’s brothers—and, to Christians, all other Christians were brothers—but it was fine to charge interest to one’s enemy. Usury was perceived as a weapon that weakened the borrower and strengthened the lender; so, if one loaned money at interest to one’s enemy, that enemy would suffer. This belief led Christians to the absurd practice of lending money to the Saracens—their enemies—during the Crusades.14
Like the Greeks and Romans, Christian thinkers viewed certain economic transactions as zero-sum phenomena, in which a winner always entailed a loser. In the practice of usury, the lender seemed to grow richer without effort—so it had to be at the expense of the borrower, who became poorer. But the Christians’ economic hostility toward usury was grounded in and fueled by biblical pronouncements against the practice—and this made a substantial difference. The combination of economic and biblical strikes against usury—with an emphasis on the latter—led the Church to utterly vilify the usurer, who became a universal symbol for evil. Stories describing the moneylenders’ horrible deaths and horrific existence in Hell were common. One bishop put it concisely:

Such was the attitude toward usury during the Dark and early Middle Ages. The practice was condemned primarily on biblical/moral grounds. In addition to the fact that the Bible explicitly forbade it, moneylending was recognized as self-serving. Not only did it involve profit; the profit was (allegedly) unearned and exploitative. Since the moneylender’s gain was assumed to be the borrower’s loss—and since the borrower was often poor—the moneylender was seen as profiting by exploiting the meek and was therefore regarded as evil.
Yet the church violently opposed even such subsistence-level lending.
During this period, the Bible was considered the basic source of knowledge and thus the final word on all matters of importance. For every substantive question and problem, scholars consulted scripture for answers—and the Bible clearly opposed usury. In the Old Testament, God says to the Jews: “[He that] Hath given forth upon usury, and hath taken increase: shall he then live? he shall not live . . . he shall surely die; his blood shall be upon him.”7 And:

Thou shalt not lend upon usury to thy brother; usury of money; usury of victuals; usury of anything that is lent upon usury.
Unto a stranger thou mayest lend upon usury; but unto thy brother thou shalt not lend upon usury, that the Lord thy God may bless thee in all that thou settest thine hand to in the land whither thou goest to possess it.8
In one breath, God forbade usury outright; in another, He forbade the Jews to engage in usury with other Jews but permitted them to make loans at interest to non-Jews.
Although the New Testament does not condemn usury explicitly, it makes clear that one’s moral duty is to help those in need, and thus to give to others one’s own money or goods without the expectation of anything in return—neither interest nor principal. As Luke plainly states, “lend, hoping for nothing again.”9 Jesus’ expulsion of the moneychangers from the temple is precisely a parable conveying the Christian notion that profit is evil, particularly profit generated by moneylending. Christian morality, the morality of divinely mandated altruism, expounds the virtue of self-sacrifice on behalf of the poor and the weak; it condemns self-interested actions, such as profiting—especially profiting from a seemingly exploitative and unproductive activity such as usury.
Thus, on scriptural and moral grounds, Christianity opposed usury from the beginning. And it constantly reinforced its opposition with legal restrictions. In 325 a.d., the Council of Nicaea banned the practice among clerics. Under Charlemagne (768–814 a.d.), the Church extended the prohibition to laymen, defining usury simply as a transaction where more is asked than is given.10 In 1139, the second Lateran Council in Rome denounced usury as a form of theft, and required restitution from those who practiced it. In the 12th and 13th centuries, strategies that concealed usury were also condemned. The Council of Vienne in 1311 declared that any person who dared claim that there was no sin in the practice of usury be punished as a heretic.
There was, however, a loophole among all these pronouncements: the Bible’s double standard on usury. As we saw earlier, read one way, the Bible permits Jews to lend to non-Jews. This reading had positive consequences. For lengthy periods during the Dark and Middle Ages, both Church and civil authorities allowed Jews to practice usury. Many princes, who required substantial loans in order to pay bills and wage wars, allowed Jewish usurers in their states. Thus, European Jews, who had been barred from most professions and from ownership of land, found moneylending to be a profitable, albeit hazardous, profession.
Although Jews were legally permitted to lend to Christians—and although Christians saw some practical need to borrow from them and chose to do so—Christians resented this relationship. Jews appeared to be making money on the backs of Christians while engaging in an activity biblically prohibited to Christians on punishment of eternal damnation. Christians, accordingly, held these Jewish usurers in contempt. (Important roots of anti-Semitism lie in this biblically structured relationship.)
Opposition to Jewish usurers was often violent. In 1190, the Jews of York were massacred in an attack planned by members of the nobility who owed money to the Jews and sought to absolve the debt through violence.11 During this and many other attacks on Jewish communities, accounting records were destroyed and Jews were murdered. As European historian Joseph Patrick Byrne reports:

“Money was the reason the Jews were killed, for had they been poor, and had not the lords of the land been indebted to them, they would not have been killed.”12 But the “lords” were not the only debtors: the working class and underclass apparently owed a great deal, and these violent pogroms gave them the opportunity to destroy records of debt as well as the creditors themselves.13
In 1290, largely as a result of antagonism generated from their moneylending, King Edward I expelled the Jews from England, and they would not return en masse until the 17th century.
From the Christian perspective, there were clearly problems with the biblical pronouncements on usury. How could it be that Jews were prohibited from lending to other Jews but were allowed to lend to Christians and other non-Jews? And how could it be that God permitted Jews to benefit from this practice but prohibited Christians from doing so? These questions perplexed the thinkers of the day. St. Jerome’s (ca. 347–420) “solution” to the conundrum was that it was wrong to charge interest to one’s brothers—and, to Christians, all other Christians were brothers—but it was fine to charge interest to one’s enemy. Usury was perceived as a weapon that weakened the borrower and strengthened the lender; so, if one loaned money at interest to one’s enemy, that enemy would suffer. This belief led Christians to the absurd practice of lending money to the Saracens—their enemies—during the Crusades.14
Like the Greeks and Romans, Christian thinkers viewed certain economic transactions as zero-sum phenomena, in which a winner always entailed a loser. In the practice of usury, the lender seemed to grow richer without effort—so it had to be at the expense of the borrower, who became poorer. But the Christians’ economic hostility toward usury was grounded in and fueled by biblical pronouncements against the practice—and this made a substantial difference. The combination of economic and biblical strikes against usury—with an emphasis on the latter—led the Church to utterly vilify the usurer, who became a universal symbol for evil. Stories describing the moneylenders’ horrible deaths and horrific existence in Hell were common. One bishop put it concisely:

God created three types of men: peasants and other laborers to assure the subsistence of the others, knights to defend them, and clerics to govern them. But the devil created a fourth group, the usurers. They do not participate in men’s labors, and they will not be punished with men, but with the demons. For the amount of money they receive from usury corresponds to the amount of wood sent to Hell to burn them.15
Such was the attitude toward usury during the Dark and early Middle Ages. The practice was condemned primarily on biblical/moral grounds. In addition to the fact that the Bible explicitly forbade it, moneylending was recognized as self-serving. Not only did it involve profit; the profit was (allegedly) unearned and exploitative. Since the moneylender’s gain was assumed to be the borrower’s loss—and since the borrower was often poor—the moneylender was seen as profiting by exploiting the meek and was therefore regarded as evil.
Seeing interest referenced positively in the New Testament confused me considering Christians' later viewpoint of it.
I'll give it more thought Harv, thanks for your post
Can you explain it to me?
. I am sure Sommerswerd knew that part of the new testament are the gospels 
