Actually, many "minstrels" pre-movies did shows EMULATING black entertainment. They were shooting for authenticity, not insult. Al Jolson was the most prominent one and the last. They loved the "black" style and I think, didn't believe anyone would accept a white (Jew) dude singing those songs and styling them that special way. Jolson was no mere bigot.
I mean, really, Suzanne here was that same thinking: how does anyone know we're the Supremes as a bunch of white girls (poor quality, but she wanted to be real while her sister and others were against it)?
https://www.youtube.com/watch?v=VwdeDZk7GJg
As for all the hype about this kind of thing:
I was aware of Jolson, but he’s about the only one I could have come up with.
Good comments and your example, good one.