"All of a sudden you have entire peoples seen as sub-human; if someone is sub-human then the slaver is justified in what he does.
Two of the most provocative areas for legacy theory are the caricatures of black male sexual prowess and sporting achievement. The suggestion is that today's stereotypical images were born out of slave owners' preference for the most athletic specimens from among their stock.
Two centuries of these stereotypes and pseudo-science have arguably left a deep psychological scar on society--both in white perceptions of black people and the responses of some black people to that projection.
Now we celebrate them as warriors and mystics. Which means we still don't treat them as real people with real problems. We're happiest when they exist only in the fantasyland of movies, cartoons, and sporting events.