But, wiithout black Africans selling their fellow black Africans into slavery, the transatlantic slave trade wouldn't have existed. It wasn't about race, it was about economics and supply/demand, in this case the SnD was for human labor. No white Europeans went onto African soil and rounded up a group of blacks, put them in shackles and force marched them onto a ship.
Had India or China been in closer proximity to Europe and the US, those two areas would have supplied the slave labor. In fact, much of India, when it was under British rule, used Indian slaves.
Yes, slavery was horrific, but white people aren't the only reason it existed.