You seem to have a really big chicken-and-egg problem here... you want morality to be universal. The problem is, "ethics", "morality", and "values" are all human constructs. We created them, we define them, we discuss them ad nauseum. They are as varied as we are. I don't think that makes them "meaningless".
I don’t have a chicken and egg problem. The chicken and egg problem arises from an attempt to pull meaning out of an arbitrary universe.
You say in different words that things are meaningful only because we believe they are. That’s fine if it helps you but it’s also circular and rather solipsistic. Your stance is also literally nihilistic: “a doctrine that denies any objective ground of truth and especially of moral truth”.
