-- how can you claim to have explained morality in any sense, with or without the supernatural?
We all learn basic morality [the golden rule] at our mothers breast..
-- Don't bite the tit that feeds you.
All other variations on morality follow.. Nothing supernatural about it.
Aside from your crudity, you leave unexplained why we have any reason to believe the lessons learned from our mothers are right, if both we and our mothers are merely primates evolved to fit a niche in the African savannah.