Is the Only Thing That Makes a Currency Valuable?

It seems to me that there's no way to avoid at least a second currency, the am. I don't know if it makes any difference, cause it can happen anyway. Or maybetha, just maybe, just every currency will be am transferable. Why is it that you have to buy oil an dollars? Is there any reason for that? Because i think that alone could be solved. If fluctuation is the only problem, it seems like you could solve it just contractory. Yes, we're the most stable economy, so you just assume that the dollar will stay valuable and have a market forever. Ono, that seems pretty solvable. I think china