It's remnant social narratives from a time where such looks as determinative of hierarchical status were obscured by religious asceticism, fanciful dress, and social mannerisms.
This is from the illustrated eroticist artist Martin van Maele in early 20th century France.
This world where sexual desire was a hidden thing buried in contrast to the class and aristocracy of society - that world is gone. However, families repeat the same basic narratives and ideas that were perhaps more believable in that world than this one. And these beliefs, ideas, and mores are still deeply rooted in our psyche.
Like motherfucker, so much of our children's songs are racist Minstrel songs. "Shoe fly don't bother me" is about a black slave who's basically a stupid farm animal that can't comprehend spiritual matters, so when the angels are lassoing people to heaven, he's telling the angels to "shoe fly don't bother me".
"Turkey in a straw" (the Steamboat Willie song) is a clean version of "Old Zip Coon" which is about a black man trying to be a civilized white man but he's too retarded to figure it out.
"Oh Susanna" is about a wandering stupid black man trying to fall in love with a white woman, etc.
Do people own slaves or take pleasure mocking black people because they are stupid? Not really. But it's just unconscious cultural patterns.
