American music is really world music. People came from all over, in vastly different circumstances from hopeful to desperate to nightmarish.
All those cultures brought music of their own and over the centuries different strands and peoples forged new things.
Take Hank Williams.
Born in Alabama in 1923, his primary influence when he was learning guitar was a blues musician named Rufus Payne.
Williams incorporated blues into his own country style and a lot of it bleeds right into rock and roll. His son, Hank Jr., says that Rock Around the Clock, the famous Billy Haley and the Comets song, is basically a reworking of Move it On Over, by the elder Williams.