I don't believe money was a single invention. I believe it was gradual. The first money was likely something that everyone (most people) wanted but didn't need, like some form of jewelry. It likely just emerged as a social phenomenon, not someone saying "get! I have an idea!" Over time, scarcity and difficulty of production made certain forms a better stand in for trade.

Metals made great money because they don't naturally appear or grow from the environment, have permanence, take a lot of labor to produce, are not easily faked, can be highly aesthetically desirable, and are mintable in standardized amounts.

The trouble with metals is transport. Doing business with neighbors was no trouble, but distance and scale of transaction compound the effort. This is why ledgers, banks, and paper money were invented.