That's a completely different aspect of money than we were discussing previously. What I'm saying is, that the earliest types of money came up by convention and not by someone inventing it.

So maybe someone wanted to have something (maybe a certain tool or something to eat) someone else had, but all he had were some rare type of sea shells. The sea shells themselves are not useful for anything, but eventually the "seller" of the tool found the shells nice to look at. Then he found someone else who wanted to trade against the shells and after some time the convention developed that sea shells could be used to trade things that people wanted.

This is completely different from a single person inventing something.