The reason people like animals better than humans is because animals can fit into any rule we want, besides maybe don't eat your own poop. You can forever imagine that an animal is grateful and loves you, even if they are really thinking 'big thing brings food' or 'yum poop', but humans can articulate thoughts like 'really, I'd rather have food than to be told how to believe' or 'I really don't appreciate that time you stabbed my grandpa in the eye', and you have to develop difficult skills such as empathy for people who aren't always perfect, which is hard to do.