I've heard about them stealing rock, but country too
Yes White people stole Country and Bluegrass too. Slaves from West African, most likely Mandingos, brought the banjo to the USA. Country music began on the slave plantations in Georgia, North Carolina, South Carolina and Virginia. Thomas Jefferson even mentioned the slaves having some instrument called a Banjo.
PBS - American Roots Music : Instruments and Innovations - The Banjo
Of course rednecks heard the slaves playing the banjo and then the rednecks started playing it. Now days stupid rednecks think that White people invented the banjo. The slaves also played an African fiddle instrument that I think is called the gogee. For some reason that instrument never caught on, but the fiddle that the Irish/Scottish White people had did catch on among the slaves. So it was the slaves that became the earliest musicians in the USA and they played in something called jamboree (we now call it jam session) which is a Jollof word for loud party or loud noise.
America's Cultural Roots Traced to Enslaved African Ancestors
Btw, it would stand to reason that the Mandingos would have been the group that would have been professional musicians, because the Mandingos had a group of professional musicians called Griots that were throughout the Kingdom of Mali. The instruments from that Kingdom included the Banjo, Kora, Balafon and the djembe.
Country music biggest stars learned from Black Blues musicians. Hank Williams, Sr., who is arguably Country music's biggest star learned from a Black Blues musician named Rufus "Tee Tot" Payne.
Hank Williams Biography
Bill Monroe, who is considered the "Father of Bluegrass music" learned from a Black Blues man named Arnold Schultz.
Arnold Shultz: Black fiddling and bluegrass music - Pete's Place
People like Johnny Cash, Elvis Pressley and Jerry Lee Lewis, all list Black Blues musicians and Sister Rosetta Tharp, who was a Black Gospel singer/guitarist as their biggest influences.
Why Sister Rosetta Tharpe Is The Most Influential Music Artist Ever | KVRX