I just need to bump this thread to say that you kind of ignored an earlier post on here that mentioned black rock musicians. The true rock and earlier jazz greats (I mean Coltrane, Parker, Mingus, Blakey Mary Lou Williams, Carter, Tony Williams, Eric Dolphy etc.) were all black and most came from dirt poor backgrounds with working class (former slave) families and usually worked in blue-collar jobs for years before making it in music.
And there are great musicians who worked all their adult lives at working-class jobs and never got discovered until after they died. My best example of this is Eva Cassidy, who worked as a propagator at a plant nursery for most of her adult life plus some time doing painting and jewelry design. (Yes, once again I’m going to mention Cassidy, as I have in many other threads.) She never made a living on her jobs singing in her spare time. Four and a half years after her death at the age of 33, an album by her topped the charts in the U.K., as did two later albums. She charted high in various other countries. She’s sold a thousand times as many albums since her death as she did during her lifetime. I don’t know how to characterize her music. She did a variety of genres and specifically told some record labels that she wasn’t going to limit herself to one of them.