I’m thinking through what I know of western history, and it doesn’t seem like westerners were ever racist in the way we characterize racism today.
The Bible guided western thought for two thousand years and makes it very clear that all human beings are related by blood. So I can’t imagine how any of the early European colonizers’ came to the conclusion that primitive people were “lesser humans” the Bible forgot to mention existed.
Long before the colonization of the Americas, western Christendom had intimate contact with black and brown people its entire history. The Middle East and Africa were largely Christian right into the Middle Ages.
But then there is this point where European whites start propagating the idea that human beings are not equal, that some races are lesser humans who can be subjugated on the basis of race alone.
How did that happen?
It’s not quite the same, but while you wait for more responses - I wrote a bit about the origin of racism in modernity and early America here: https://reddit.com/r/AskHistorians/comments/hmo222/_/fx7vyhz/?context=1