Slavery can be a humane and correct element of a society, but only in a monarchy, where every one is a servant of the crown. In such a society slavery is just the most extreme form of servitude. And slavery can only be humane in the case where the monarch is the proverbial Philosopher/King.
In the United States of America, founded as a representative democracy, where all people are endowed with life, liberty and the pursuit of happiness there is no room for slavery.
So god makes distinctions like that? ....nevermind...i don't want to change the topic here.