I think looking at how things in the animal kingdom work and using that as a justification for our actions is a very low bar. We have the cognitive and emotional ability to understand that things like murder/rape/etc. are wrong do we not? If you just take a small step from that and recognize the sentience of animals, it doesn't seem too unreasonable to afford them the same respect.
PS: I think the idea of good/evil is pretty reductionist to begin with, but I understand it's a common way of looking at things