We are arguing details that I am not sure are relevant to my main point to this thread (not that they aren't interesting).
My thesis for this thread is that moral values don't have to stem from a objective universal truth to be real values. (I am rewording "absolute" to avoid the earlier confusion).
My moral values are just as sincere, important and just as much a part of how I see the world as yours are. The only difference is that I accept that my values don't depend on, or represent any universal truth.
I think I disagree with the importance you are giving to the difference between cultural values and personal values. I think I understand what you are getting at... I don't know that it matters really to the core of our discussion.
I could certainly imagine a world where humans weren't social animals. Each human could have a different set of moral values independent of every other human. I think this form of moral relativism would lead to a quite a different human experience.
But the fact is that human cultures do come with culturally defined moral belief systems that matter. That there is a general consensus in my culture that rape is a serious crime (and should be treated as such) certainly gives power to my belief that rape is a serious crime. If I were the only one that felt that way, there wouldn't be much I could do about it, but the fact that it is a general understanding has a practical impact on the society I live in.