Too bad you missed econ 101 .
Something of value & rare like gold was the barter from antiquity
Some primitive societies use things like cowrie shells, salt or something to motivate an exchange.
Whores use pussy.
A safe place to store the more valued things like gold gave forth banks, lending & credit etc. Fiat currencies like our federal reserve notes & computer accounting lost the notion of barter & value & empower governments to alter the balance.