Re: hurting people, torture and killing
My take on this:
The only difference between humans and animals is a consience (zameer). It is that conscience (zameer) that is used to keep our animal instincts restrained. Without that, humans are simply highly evolved animals.
So to answer your question, humans don't learn to be inhuman, they're born like that. It is hard-coded in their nerves. What makes us inhumane is our failure to learn how to use our conscience to restrain our animal instincts.
It is a constant war between our animal instincts thats Allah SWT has coded us with, and the conscience (zameer) that Allah SWT has gifted us and instructed us to use it to curb our animal instincts.