A few hundred years ago, slavery was the norm.
But today it is easily seen as a barabism, and we blame old generations for having done that, without being able to understand their point of view. Because it's so hard to imagine how it was in the eyes and brains of that past time, from our fresh point of view.
So, to make an analogy and try to understand the past point of view, let's imagine that in the future, new generations wouldn't tolerate any ownership of the land anywhere on Earth. Because the land being alive, would fall onto the general rule that no entity of any kind will be allowed to own any form of life, because it would be considered to be slavery. So then, we would be seen from their perspective as primitive barbarians, just like we are tempted to see the slaves traders of the past.
It was another time, with another kind of people, that we today are not anymore, that's why we changed the rule and banned slavery. Not because it was "bad" or "inhuman", but because it suddenly became not fashionable anymore.
So be careful with judging, through time and involving people, it is particularly useless if not totally impossible.
L'esclavage - Partie 1, par Nota Bene https://youtu.be/wqOy31A7Rjw
L'esclavage - Partie 2, par Nota Bene https://youtu.be/d8CGP2ZrvsE