As Yaro pointed out, you are wrong about animal behavior and how social structures and mutual cooperation can be highly beneficial to an organism.
We are creatures who, like many other species, behave in a social way because it has evolved in us and that in no way means we have "stepped outside nature".
Altruism, which is at the very heart of morality, is an evolved trait in us just as it is in wolves. "Greater love hath no man than this, that a man lay down his life for his friends," we are told in one of the many holy books. It is unsurprising that the morals that work also obey the iron law of survival of the species by being about altruism, self sacrifice for the group, and the protection of the young, among many other things. If they didn't we would have evolved another scheme that did, or died out.
What is called morality is easily explicable by only the world that can be observed. To add an element, especially an element that is invisible and beyond proof or reason, is of no use and should be avoided.