That's a long time unresolved argument in philosophy. IMHO, if there is no such thing as inherent value, you have some other problems logically.
This is on the cusp between philosophy and religion. But we end up there in discussions of values, morality and conscience. We end up there when we examine and question our values - which is a major part of a basic discussion of religion, faith, and reason.
Regardless, asking why the golden rule is a paramount value is a valid question. Why do you hold this value as highest? On its own merits or because of some greater value? If there's a greater value, what is it and is its value dependent or independent?
what according to you, is morality?
Doing what is right as best I can discern it at the time. Its greatly furthered by examining my values and what they are based upon.
Sorry to be blunt, but is this another reductio ad absurdum, à la uncaused cause?