Why is animal cruelty wrong and illegal?

I got lost somewhere around, "Something that is repulsive..." It is wrong because they can't defend themselves in most cases. Even if they could, they likely don't have the chance to. Human's can defend themselves in some cases, so I guess that null's my previous point. Maybe because it is inhumain..? Killing isn't a humain trait..

killing IS a humain trait.

Why?

Simple, in the past, before all this animal cruelty existed.

Humans killed, to survive. Does that make us less humans than we are now?

No we are still the same animals.

We are animals with free will and a conscious mind of self.

Doesn't make us any different. Other than enhanced intelligence.