I say "arguably" parenthetically because indeed people will argue the point.
As for me, I've always known - somehow - that rock n' roll came from Black music. I knew that the white folks who are regarded as pioneers - Elvis, Buddy Holly, The Beatles, The Beach Boys, The Rolling Stones, etc - were inspired by the likes of Bo Diddley, Chuck Barry, Little Richard, and (literally) countless other Black musicians of the early 20th century.
Rock is known to have been the fusion of black music (blues, boogie woogie, jazz, gospel, R&B) with white (country western and traditional folk). Indeed - in a time of segregated radio stations, it was quite controversial to make music that derived elements from both Black and White musics and appealed to both audiences as well. Perhaps this is also what all the fuss was about when Elvis shook his hips on TV - moves that he learned and appropriated while obsessively attending events at Harlem's Apollo Theater.
Now, it's clear enough that rock music has been mostly dominated by white people since it became popular in the 50s; but it's important also to remember its roots. I think of it this way: the modern pizza originated in Naples, Italy, sometime in the late 19th century. Folks in New York and Chicago later used those ingredients, recipe, and method to create something different. Similar, but definitely different. And perhaps better. But we'll still always acknowledge that it started in Italy!
So, too, should we remember the origins of Rock n' Roll.
That's all I have to say about that. Now I'll let Mos Def take it away.