> are just liberties we've decided we like especially well

Why do we like them? Why wouldn't we prefer to be slaves? Where do our modern intuitions about rights come from? Whatever the origin of the "like especially well" that you mention, that origin seems fundamental. If you study all the peasant revolts, going back thousands of years, you'll note how naturally people invent the language of rights -- it seems to arise spontaneously during each revolt.

And why do people revolt? You can't simply assume that they don't like being raped and enslaved -- you have to explain why they don't like being raped and enslaved. And whatever your explanation is of their feelings, that is the origin of rights.