A good currency serves two purposes: a good medium of exchange (easy to transact, easy to find someone willing to accept it in exchange for goods and services) and a stable store of value (worth ~the same yesterday as today). They are distinct purposes.
You’re describing the former (finding someone to trade with) but actually talking about the latter in your point about “imaginary value” of money (as distinct from stocks). So I’d offer a small addendum about the value of money being imaginary: the guarantor of a currency plays a huge role in making the value real, in the sense that they are obligated to accept it when you use it to pay taxes.
Likewise commodities like gold are a somewhat stable store of value (disregarding supply shocks for the moment) in the sense that if everything goes to shit you can use them to make shiny baubles (or semiconductors).
Notably this is not the case for stocks, which is why stocks aren’t a good currency. (Also why crypto isn’t a good currency but more like a stock).
Can Pokemon consent?