completely true. No society is innocent of this. One good example is slavery - I myself was surprised that chattel slavery was common everywhere in the world and it was the west that had the mental capacity to stop it.
Perhaps in history. But we humans have the ability to think and adjust our behavior. We didn't kill all the horse-people when we invented the car. It's likely that in the future we could be able to move past all the horrible things we do to each other.