I think currency acts as stabilizing project, back in barter and trade times, people only had what they tilled from the ground, hunted from the land, or drew from sources of resource to exchange with each other
Say, a goat for two chickens and a gallon of milk
however, to one person, a goat is far more than two chickens and a gallon of milk
a goat is three haybales, five loaves of bread and a turkey
and there were always economic disparities and conflicts due to an instability of Value agreement
which is what Currency sought to rectify
then, using "Trust" as our Level 0 fulfillment, we all agree that 1 dollar, has the exact value of 1 dollar