Since ive just started on my studies in ethnology (an academic field at least in my country, which is the studies of cultures and identity), i have to reply too.. i got interested in what you wrote.

In what way are traditions largely invented? How is culture invented like race was invented? Aren't all concepts invented, but they all reflect/describe the reality in some way. Some better than others.

So how shall one view the diversity of humanity?
What i like about using ethnicity as a guidance to viewing the world's diversity is because then I am norwegian rather than White, and my friend is a somali rather than Black. That way it can counter the stereotypes, stigmatization(sp) and prejudice attached to highly generalized categorizations. Instead it encourages the understanding of someone's identity ("he is somali") to a greater extent than what's the case with more generalized groups ("he is black").

Perhaps it wont transcend so easily, what i am saying and the way i see it, since norwegian culture doesn't have the use of black/white as you do in usa. (because of your history)