What about the fabulous Nat King Cole? He was certainly a crossover. The Ink Spots, Pearl Bailey, Eartha Kitt, Cab Calloway, Johnny Mathis, Duke Ellington, Louis Armstrong, Lena Horne, Sammy Davis Jr, the Dixie Hummingbirds, Brownie Terry and Sonny McGee, the inimitable Ray Charles, and so many rock'n'rollers -- Wilson Pickett, Chuck Berry, Bo Diddley, the Temptations, the Supremes, the Four Tops -- the list goes on and on of black entertainers who pre-dated MJ and who had vast white audiences. I came from somewhat "negro"-phobic parents, but managed to see most of the above acts -- live -- in my teens and twenties.
Your list is impressive, but you missed a biggie: Ella Fitzgerald.
My grandparents loved Nat. He truly crossed over, IMO. Great talent, beautiful songs.
You also left out Soul Brother Number One, without him, there’s no MJ.