Also, while we always talk about black slaves, and not to lighten what was done to them, there were also many white slaves. The irish, for example, were used as slaves for a period.
Also, back then there were press gangs and indentured servants. They often had it worse than the black slaves... in that black slaves were treated as property with value, the white slaves were viewed as disposable, and so if there was a lack of food the slave owners would protect the "property" first and let the white slaves die.
again, this is not to make light of black slaves in any way, but the way it's discussed you would think that all whites owned slaves when that's simply not the case.. but it is only the black slaves we still hear about nearing 200 years later.