When a tree falls in the forest, does it make a sound. If we don't have a moral compass which is God, It is still there because truth is still truth whether it you believe or not. A hat is still a hat and a tree still makes a sound.
If there were no people, there would be no morality. Actually, I should say "sentient beings" instead of people. On earth, anyway, people are the source of, reason for, and definers of morality. It really couldn't be any other way.