Context : MusicalStuff
Quora Answer : African-Americans invented three of the biggest genres in the world: jazz, rock, and hip hop. How did one marginalized community have such a major cultural impact?
To add to Peter Losh's pretty good answer, I think the important point about the black community in the US is that they inherited two great musical traditions. They brought African music with its rhythms. And more importantly, its approach to, and valorization of rhythm. And then, in the US, they were also exposed to (and in some ways, force fed) the whole European tradition, of church music (hymns become gospel), "common practice" theory of harmony etc.
Being the inheritors of both of these traditions, the black community in the US has had a lot of scope to experiment with different ways to recombine and integrate them. Such as adding a rhythmic emphasis to how "ordinary" instruments like pianos and trumpets are played. Or playing microtonal "blue notes" (with echoes of African microtonal scales) on guitar. Etc.
The African community now has a very strong musical tradition passed from one generation to the next (don't underestimate how many people who are big in hip-hop have parents and uncles and grand-parents who were jazz, soul and funk musicians or DJs. And who learned music playing gospel in church)
But I think it has something else. Which is also its inheritance. It has a sense that music is open-ended. That you can and should bring in new elements, experiment with new sounds, technologies etc. when making it.
Black culture has plenty of "tradition". And the usual complaints about "the noise the kids listen to these days". But I think musicians from these communities are aware that their job is to be doing something new. Not just be traditionalists, playing retro sounds. You respect the elders by digging in the crates. And sampling the classics. But then you "flip" it ... you make something new and different and your own out of it.
Peter Losh's other good point is to emphasize the parallels with Jews and Gypsies in Europe. I believe that both of these communities / cultures are a constant source of inspiration and reinvigoration to European music. And again, it's because their mobility means that they have picked up music in one place and brought it somewhere else. For maybe thousands of years, they've helped to cross-pollinate ideas and styles within Europe and the middle-East.
Both black people in the US, and gypsies and Jews in Europe have "betweenness centrality" with access to more ideas and the challenge / opportunity to put them together in interesting ways.
EthanHein writes a lot about the "whiteness" of the academic musical establishment and their rejection of it.