I don't believe that. I believe people are afraid of something that is strange or abnormal (abnormal: as something / someone that stands out from the norm), because it is a mechanical reaction. That reaction is common even in animal kingdom: anyone that lived around numerous animals / pets can testify. Once you know more about the thing or the person, you are not afraid nor have a general dislike anymore, and you coexist and even start to like.
Humans are social: you can taught them to counter their inner reaction, or change their ways by experience.
Racism is a set of beliefs, a some sort of ideology. Nobody is born racist: you become one. And you become one when it is taught. It is taught when you need to pretend that people are not equal, mostly to justify the domination of one arbitrary sort of people over one other arbitrary sort of people.
In France, I think the Racism theory started in the early medieval age to legitimise the reigning nobility (mostly germanic people) over the enslaved people (the gallo-roman)*. Feudal society was kind of a some sort of slave society back then.
Then... the Black Plague destroys this system. The people found out clergy was a mascarade (monks are not immune) and religion lost a lot of power. Catholicism cannot justify the death of so many people in all states of society: the nobility, the clergy and the third one. This lead to new pagan beliefs like the Grim Reaper. With less nobility, people started to act on their own. Basicly, the Black Plague lead to the Renaissance and the Reformation.
* : You will be not surprised that the belief become popular among germanic people, mostly Prussia, and used it and developed it. and leading to premise of WWII.
After the Renaissance, the Feudal system was not a slave society. All that racism theory was kind of forgetten because they didn't need aymore, or probably they could not use it anymore because nobility wasn't all that frankish anymore... Don't worry, it is making a come back! Racism theory was recycled to legitimise the slavery of black people. Normally, you cannot have a slave if they share the same religion (muslim had a lot of slaves, but slaves was automatically free if they converted), and christians should do the same. Except if you manage to say that some sort of people (the blacks) are in fact, not people! So you end up with humans converted to christianism that are not considered as people. Yeah, this is not making sense, but I guess it was good enough for the Pope back then.
What surprise me is that "germanic" protestant (English, Dutch) people were harsher on slaves than "latin" catholic people (French, Spanish, Portuguese). It is the other way when it comes to war. I guess the former saw the slaves as inferior people, probably inherited from the Vikings, but the latter saw the slaves as submitted people (like unlucky but equal), probably inherited from the Romans? I guess religion played a role: USA is far from being a mixed country, contrary to the rest of the new world, and it is the only one being protestant. Coincidence?
(I like being contraversial. The fact is: I don't know, I throw it out there. I am far from being knowledgeable on the subject. I just wanted to tease the Americans).
In brief: I believe that all people are naturally afraid of what is out of the norm, but it is not racism, just an instinctive reaction. With exposure, you find that thing "out of the norm" was harmless, symapthetic and relatable. Racism is a teaching, even an ideology. The purpose was to legitimate either the supremacy of something or the inferiority of something for a specific agenda. People are not born that way, those beliefs were learnt. And the beliefs pass on because parents tend to pass on their believe into their children. This is what I believe. I might be wrong, being cynical or idealistic. I don't know.
I really agree with everything Aurelesk said.
About Germanic-Viking issue, they are also kings in Russia, Spain, Brazil and Mexico. Any of this countries had a strong germanic heritage, but for some reason the nobles of this kingdoms had Germanic heritage (the blue blood). I guess our modern racism is not just pointed to white, but inside white community, it is pointed to the Germanic. Civilization game also do it, as it have almost the same numbers of Germanic Leaders than No-Caucasians leaders.
Some of what you said is right and some wrong. Americans as a whole aren't a racist people. (I'm not) In fact most of us aren't (or are in a different way).
Some people have become racist in trying to stop racism. (Essentially flipping the roles) There are some who hate non whites. However, they're a minority. For some reason however a lot of people hate whites (Bc according to them, we're awful humans),therefore being racist themselves. They embrace what they hate most. I'd say I'd fall into the majority who aren't racist at all. I see people as people and judge someone by their choices, not by innate traits from birth. In fact most of my friends are second or third generation Americans, half of them are four to 13 years younger than me as well. (Check my bio)
(Also, yes America is mostly christian.)
Also how is France right now. My friend went last summer and loved it.
I think it is very hard to don't be racist if you born in XX century, I'm not saying we are this kind of racist.
But it is possible to have smooth racisms everywhere, as said Aurelesk, it is a sort of ideology, you can have full pack or just a few of it.
The Brazilians have the "3 races myth" of Gilberto Freyre, but Brazilian Black Movement hate it because they think it build brazilian way of racism.
How is the Brazilian racism? First of all, it is smooth.
Freyre often say in his book how Brazilian isn't racist if we look to the USA. (Black Movement would reply one error don't justify another).
Freyre also say, as a mix race, we are all already as a big familly.
And despite the Black have a lot of troubles in his life just because they are black, a lot of Brazilian will say racism isn't a thing in Brazil, they understand racism just "Us-American" way to be racist, they though to be racist we need to have a KKK uniform or something as that.
Of course the KKK members are the most racist possible, but it isn't the only way to be racist.
For example of this game Civilization, it is clear this game don't want to be racist, they at least have some Civs from Africa and Native-America. (Other games as Rise of Kingdoms just have Euro-asiatic civs).
But, despite the Civilization had give the first steps against racism (and also against machism), it still need to give a few steps more to be not racist at all.
Jest one question; do you hate Jackson? Because for all his faults he had some great qualities. (Loyalty was one of them)
I don't hate anyone, also we need to remember I'm not an expert in USA history.
How I discover about Andrew Jackson? First it was a Facebook post talking "Why Trump like Andrew Jackson?". (I need to admit, if Trump like someone, it isn't a good first step

).
And now, searching about Seminole tribe, Andrew Jackson appear as the foe in this narrative. But I don't hate him.
Indeed I would like to see Andrew Jackson as alternative leader to USA.
I guess the only way to overcome racism is speaking about that. I really want to have a bunch of African and Native Americans civs and I would like to have an Andrew Jackson to destroy with some Haitian's troop. (This is the game I want to set and play

), yes, it can sound racist, but it is just a game after all.
Other players can use Jackson to conquer the 5 civilized tribes, but, in both cases we will playing thinking about racism in theses scenarios.
And just thinking about racism we can overcome it.
I think Civilization is avoiding this Race thema for too long, everyone here agree how old is slavery, but this game don't have any mechanic to play with it.
Blacks, in the Slavery history, can be Heroes and Villains too. (As I saw in the internet, few people see it, some just say the White are bad, other say just Black are bad, but in real world, both can be bad and good guys.)
I also would like to see L'Overture as a Black heroe against the evil of Slavery and also want to see Ghezo from Dahomey empire (From the Slavery coast) as this history villain.