An instinct towards fairness is no more supernatural than it is mysterious. We’re an evolutionary relative best fit, and a pack animal. That means that our species requires a certain degree of selfishness, along with a certain degree of altruism. Further, any species that was omnicidal, would be unable to form cohesive social groups in the first place. Empathy serves as the basis for morality, not Quetzalcoatl’s say-so.
What we know of as morality is, in effect, bio-mathematical. The closer a species is to its Nash Equilibrium, the less like it is to play zero-sum games as a rule. And behavioral algorithms that lead to maximal species-fitness, get passed down.