I've always admired animals for their ability to be totally honest. Look at a cat, for example. If you call a cat and it's not interested at the moment and doesn't want to come to you, it will simply ignore you and walk away. Human interaction requires more... tact, which is something I feel I seldom have the energy for. In a sense I feel that humans aren't comfortable being around you unless you're willing to wear a mask for them, hiding your true feelings or intentions.
That's just one of the many traits animals have that I can relate to and appreciate. Couple that with the truly despicable acts humanity is capable of (and has regularly committed since its inception) and I'd say I definitely emphathize far more with animals than humans.
Also, the concept of having children has always been a bit disgusting and disturbing to me. But I think of my cat almost like my "baby" because I love her so much. So in that respect, I sort of relate to the human feeling about kids, I think, from both the loving and the protective perspectives. If anyone tried to hurt my cat, or any other animal in my presence, I think that would kick me into the same sort of atomic-explosion-unstoppable-pain-train that most dads (and moms) say they'd turn into if anything happened to their kids. So in that respect I guess you could say that my feelings toward animals actually help me relate a bit to humanity.