The Muslim empires of India attempted to systematically destroy Indic culture. Not a single Great Temple exists in the North (which can equal the the grandeur of the Great Temples of the South). The Mughals were imperialistic tyrants, nothing else. They hated India.
If that's the case, it's still remarkable how religiously tolerant they were. At its greatest extent, the Mughals controlled almost all of India (as shown by the map earlier). The fact that about 80% of Indians are Hindus today suggests that they were certainly not forced to convert and were allowed to continue practicing their religion.
When foreign empires capture distant territories, they will often (sometimes passively) introduce or support their own culture, or lead to a fusion of cultures. This is done through, for instance, the patronage of Persian/Turkish/Arab style art forms, etc. the use of "Islamic" style architecture for new buildings financed by the rulers, etc.
If they did actually destroy temples and/or other cultural buildings then that is extremely unfortunate. One reason I can imagine that this initially happened (ie: in Northern India) is that the incoming Muslims saw Hinduism as an idolatrous religion, and as most people know, the Abrahamic religions state clearly that they do not tolerate idolatry.
However, I believe that the title of "People of the Book" was eventually extended to the Hindus, which is one explanation why their religious community was able to survive and develop despite Islamic rule.
Then why is it being presented as a miracle? The uncle is stuck in a logical paradox (kinda, there's no intellectual need for him to convert).
How can the uncle convert to Islam if converting would then disprove Islam? He can never believe the message of Islam (in order to convert), because believing it shows that Islam is not true.
You cannot reasonably believe, because if you do, you disprove that it warrants belief!
Muhammad's (pbuh) uncle, Abu Talib, loved Muhammad (pbuh), and protected him, despite disbelieving in his religion. He could have ended Muhammad (pbuh) and his followers' isolation from the rest of their tribe simply by reciting the Shahada (testimony of faith, that there is no god but Allah and that Muhammad is his messenger). However, he believed so strongly in the faith of his forefathers that he was unwilling to give even that much respect or attention to Islam.
The revelation given to Muhammad (pbuh) doesn't say
why Abu Talib will never declare the Shahada, only that he never will and will never be among the Muslim community. The assumption that you're making is that if someone declares the Shahada and that they claim to others that they believe in the message of Islam, that Muslims can say "we don't think you're sincere" or "we don't believe you." Once a person declares the Shahada, they are considered Muslim by the Muslim Faithful. If they didn't mean it, and practice Islam, despite disbelieving in it, then they are among the hypocrites, which the Qur'an states will be among the losers in the Hereafter (because they profess to believe and disbelieve).
The question that you have to ask yourself is, if this wasn't revelation from God, why risk making such a comment and leave this
huge potential threat open.
Even on his deathbed, Muhammad (pbuh) tried repeatedly to convince him to accept Islam. Members of their tribe however continued to interject and say "will you really give up your forefathers' faith?" Abu Talib was unwilling to give up those deeply held beliefs and died as a non-Muslim, which bothered Muhammad deeply (pbuh).