Please don't misunderstand me.I was one of those kids who brought home every wounded or orphaned animal I found as a kid and raised or nursed them back to health. I haven't changed much and have kept animals most of my life and feel they should be treated well. But to claim they have a sense of "humanity" is a little strange to me and anthropomorphizes most (if not all) beyond reason.
Did the dog in the example you mentioned not take the flavorless treat because it thought it was "unfair" or because it simply didn't find the treat appealing? Even if it was due to it being unfair, that's hardly a human only trait. My daughter had a pet rat who would turn down treats it liked if it thought you had something else that it liked even better.
Dogs have been domesticated for a very long time. Longer than recorded history. When I was young I read that dogs wagging their tails when they are happy was not something that they naturally did. I never really believed it. But I had a wolf hybrid, when I was in my late teens, who didn't wag his tail. I also found a stray German Shepherd who was on his own for most of the first two years of his life. He never wagged his tail either. I currently have a two year old Doberman who was given virtually no human or animal contact for the first 9 months of her life and was in a shelter for over a year after that. I've had her for close to a year now and she has just recently started wagging her tail(nub) as she's seen our other two dogs doing it.
Dogs are pack animals and have a very strict hierarchy. They protect the pack and, in most cases, their humans are the alphas.