There are no gray areas between what constitutes a human and a non-human animal.

One can feel absolutely no affinity or affection towards an animal, yet feel a great deal of affection for humans.

Just as the 'love' of animals does not make one a 'good' human (see Hitler, A), nor does the absence of emotion towards animals make one a 'bad' person.

To reference my first line, there are no gray areas between what constitutes a human and a non-human animal. Yet it's fair, I think, to say that some people love animals more than they love humans. To trot out a tired scenario, imagine a child and a person's dog were both drowning, and the owner of that dog could only save one or the other. Would it be an act of inhumanity to allow a child to perish in order to save a dog.

Is a dog's life more valuable than that of a child?

I would think that obviously no dog's life is more valuable than that of a child, and anyone saving the life of a dog over that of a child is in no way a 'good' person.