Money is a store of value.

Value is a property that society sets.

You don't want your storage of value to be common, or easy to get, or disintegrate, so you look for a good symbol for it.

Rocks are one thing. Rocks worked at one point, but rocks are easy to get. So rocks were discarded. But gold, silver and copper require a massive effort to mine, refine and finally mint.

Bronze and Iron were tried at some point ... but they both rust and disintegrate. But gold, silver and to some extent, copper don't rust in the common way that iron or bronze does. They tarnish ... which actually protects the base metal.

So ... we have the reason why gold and sliver are far superior as stores of value than any other item short of direct barter.

The only thing money is ... is a middleman in the trading of goods.