Reading your edit... I believe that there exists some X such that X developed through natural selection, X does not depend on any particular knowledge, X can be investigated scientifically, and for any moral intuition M possessed by a human in the real world, there's a high probability that M depends on X such that if X did not exist, M would not exist either. (Which is not to say that X is the sole cause of M, or that two intuitions M1 and M2 can't both derive from X such that M1 and M2 motivate mutually exclusive judgments in certain real-world situations.)

The proper relationship of X to the labels "objective morality," "moral nihilism", "moral relativism," "Platonic Form of Good", "is statement" and "ought statement" is decidedly unclear to me.