Man has been made more and more civilized as the years pass and things once considered morally acceptable are no longer viewed that way by the vast majority. It amazing how far we have come in a 150 years(Bible very old and full of cruelty and a form of justice very illegal today).
I'm hopeful that as time goes on we as a race will grow in understanding because with big brains we got more good than bad moving us forward in time.
With modern technology leading the way to better exploit our renewable resources I think we will see gadgets replacing any need for slavery of any kind.
And then AI can do everything for us perhaps wait on us hand and foot,, preform remarkable surgery, and whatever.