Logic is part of us so it does not matter why it is true for we have to live with it.
That is the only foundation.
Morality, as another form of logic, is built on that foundation.
Logic is fundamental in a way that morality is not. In other words, without thinking we cannot determine that hurting a baby can be wrong or is wrong.
Morality is part of us too so it does not matter why it is true for we have to live with it. That means it is human but not human as in a man-made thing. Sight is human but not man-made. It means we are better than any God. Trying to make morality depend on God means man is trying to do it and that is what I'd call a man-made morality! Trying to create morality by delegating it to God is inventing morality.
Morality is based on free will. Surely you have the ability to defy morality and even the ability to not believe in it at all. But the latter is not possible. To throw out moral rules or morality as a general value leads to you treating the affirming of them as immoral.
By the way, it is strange if we can defy morality to kill millions and cannot be a recluse who has no belief in morality! What does that say if there is a God providing us with free will?