There are examples of it being emergent phenomenon, yes, but when you look closely at how the cowrie shells moved around, you'll see the behavior of state actors. The vast majority of the shells were stored in a single dwelling in the settlement with thick walls and often below ground. These dwellings were guarded by warrior-class members of the societies, The dwellings were connected to a single family or even just a single person: a warlord or monarch. If it walks like a duck...

Okay, so money follows a power law distribution (like many natural phenomena), where wealth tends to concentrate. And early people who used money needed a bank (safe/guarded place) to store it in. Your argument seems tautological, "The state uses money, therefore money is an artifact of the state". This feels like a "Wet sidewalk causes rain" situation.

It's not tautological, it's just observing the thing a lot of people with libertarian mindset tend to forget - that state is a natural step in evolution of groups. When your society grows bigger than several dozen members, you no longer can have everyone deal with everyone else personally. You can't spontaneously coordinate larger groups of people, so a mechanism of coordination naturally arises. This mechanism pretty much always is a form of state.