I think it's all relative. I mean, I care(d) so much about my German Shepherd and cried myself to sleep when she was gone. I also cried when my grandfather died. I truly think that it's the situation that ultimately determines my thoughts and reactions about humans/animals.
I just really feel for animals, because most of the time they can't tell you that they are hurting...or where. With the exception of limping or something like that. They don't complain. They are soft, furry, and constantly give you attention...but there are also those that can bite your head off.
I will say this. I don't value an animal's life more than a human's, but it is much easier for me to deal with a human dying than an animal (with the exception of my family, of course). I guess that's why I changed my major from pre-vet to Nursing.