Rights exist, but are contingent on material conditions. Different systems have different rights conceptions not because they "agree" to have them but because they arise from the social and economic relations. This is true even if the individual morality of people differs massively from those conceptions of rights (though often people's personal morality also shifts to be more compatible.)

Now this doesn't mean there aren't universal human values. Most humans would prefer not to be shot in the head. But social and material relations can convince them to get shot in the head as a right and true thing to do, or conversely, destroy others to maintain their own perceived security.

This also doesn't mean there is no "perfect morality" given by god or nature or whatever. Maybe there is. But if you want to live it you're gonna have to accept it's not hard coded to happen while you sit around or make tiny individual gestures.