Really…are we going to act like white Europeans didn’t hold themselves as superior to Africans the moment they stepped foot on the continent, long before the salve trade began? Plenty of writings about Africans being savages or uncivilized from jump, before the real exploitation even got started
ETA: slavery may have been capitalistic, but where they got the labor and how they viewed slaves was based on white supremacist thinking. They didn’t treat indentured servant white folks this way at all, even gave them a (rigged) way out, black folks, they rigged your way in - everyone born to a slave woman was a slave
They didn't treat indentured servant black folks this way at all either. Blacks were suing for and getting their freedom in those early years just like whites. So what clicked? I'd say the profit motive tipped things.
Really it wasn't even until the Royal African Company around 1670-ish, and then everyone and their mother got into the Slave Trade for money around 1700. That's when you see a shift. Look at these numbers ...
Estimates
This isn't to excuse any white supremacist thinking. But I'm just saying that the magnitude of the situation was greatly increased by the profit motive.