to get back to the original question:
Slavery can be blamed on the white man very convincingly, BUT:
There were black slave owners (of black slaves) in the US.
There were black slave owners/traders of black slaves in Africa, who sold them to white merchants, usually to work indigo/rice in S. Carolina, (especially) sugar in Jamaica/Barbados/etc, and less frequently tobacco in the chesapeake. Like everybody said, started from POWs, then a frickin' cottage industry sprung up to support it.
In North Africa, there were blacks who owned white slaves (captured in the mediterranean, including some americans), and they also owned black slaves.
IMHO this doesn't mean that it's okay for whitey to own slaves because the Africans did it too. Though I remain thoroughly convinced that morality is just the handmaiden of circumstance, so those who needed slaves found it to be morally just fine, while those who didn't often thought it awful.
If you're interested in the debate, read Thomas Jefferson's letters on the state of virginia about slavery (i'd find the link but i'm a lazy asche) or "The Wolf By the Ears."
FYI, Jefferson has been accused of being a flaming hypocritical racist because he made babies with Sally Hemmings while thinking Blacks inferior.
First, Sally Hemmings wasn't black, and second, a jefferson (there were twenty four i think in three counties) made babies with Hemmings; not necessarily Thomas. Very unlikely it was our third president, in fact.
Okay, this is tangential now, so pay no attention 🙂
hope it helped