Superstar’s a relative term of course, but who was the first black entertainer who was well paid and would have been known to most people who read newspapers? Master Juba was very popular in his own lifetime but he lived before mass media- I doubt many people in the south and the provincial north ever heard of him.
Was Bert Williams very famous to non New Yorkers? (I know he refused to play the South, which probalby added to his fame among Southerners.)
Of course an argument could be made for Jack Johnson, but I’m more interested in entertainers than in athletes. I’ve read the description “first black superstar” for entertainers ranging from Hattie McDaniel to Paul Robeson (probably the first black entertainer to openly embrace political activism) to Stepin Fetchit, but I think it would probably be earlier. Josephine Baker has gotten the billing to, but she was far more popular in Europe than in the U.S.A…