@kyriacos is simply putting out the information. Of course morality is simply an abstract concept synthesized from humans. It is nothing, just as good and bad are nothing. You don't look into nature and see remorse from the wolves who eat the sheep. You don't see the bear feeling bad for eating the fish. Of course here are things we would consider "unjust" if it were happening all our lives, it would be normal.
The Aztecs would tear peoples' hearts out for their god. Was that wrong? Not for them, it was the best they could give. You mention the Holocaust, there are many worst events than the holocaust; I'm white and my ancestors infested Northern America and wiped out an entire race almost. Over land.
Animals do the same. We are animals. We are not above the others.