I have less than zero patience for oppression-complex historical revisionism or Marxist cultural relativism.

90% of the population

Source?

tens of millions dead across the continent

That would be a neat trick, considering there were not that many people in the Americas at the time of Columbus' arrival.

torturing, burning and hanging people by their genitals

Yeah, some of the conquistadors were dicks. That does not in any way make them the moral equivalent of the industrial-scale practice of human sacrifice that the Aztecs were using to keep their own conquered enemies under control.

sacrificed people not out of cruelty but because they believed they had to

Well that makes it okay then.

advanced mathematics, engineering and metallurgy

Then why were they living in mud huts and killing each other with stone axes?

someone born centuries ago would sit there miserable because they didn't own a smartphone

No, but they might be miserable because half or more of their brothers and sisters would have died before reaching adulthood, or because they had a gangrenous infection that was slowly killing them and causing them immense pain as it did so, or because they were enslaved and being worked to death in a field.

Our modern society may not be perfect, but all of the innovations and developments that we have access to are the result of generations of desperate, brilliant men working and experimenting in order find ways to make their children's lives easier and less miserable than theirs had been. That is the fundamental basis of all of human progress.

Try telling any captured Tlaxcaltecan child who was about to have his heart carved out that being raised by nuns in a monastery is no better than what he is about to endure. Try telling anyone dying slowly and painfully of an illness that is today easily treatable that he is luckier than a man who gets to live into his 70s and watch his grandchildren grow up. Try telling any mother who lost half her children to easily preventable diseases that her emotional devastation makes her no less fortunate than the mother who has to manage her healthy child's smartphone addiction.

The Spanish were morally superior to the Aztecs because, despite all their own persistent flaws, their ancestors had already lived through the epoch of human sacrifice and solving problems of food scarcity with mass killings, and they had learned their lessons from it. The notion that they should simply sit by and allow the industrialized human sacrifice and abject poverty to continue unabated because "iss dey culcha" is no different from saying we should allow crazy woke bitches to mutilate their own children in the service of trans ideology because they believe they have to.