> Historically, states and credit-based money came first. THEN came the unit of account and medium of exchange money that you are talking about.
Actually, the Wikipedia page on "fiat money" (if that's what you're referring to) says: "Fiat money originated in 11th century China" [1]. There were many commodity currencies before that.
> Going back to the original point, can you go to a deserted island and make "money"? No. You need society. You need government. You need an economic system. The money is only partially "yours".
That's if there is only one person on that island. If more people live on the island, they might start trading services and use some some improvised currency, e.g., coconuts or seashells. In this case, you have a society and money, but not necessarily a government.