What allowed currency in the ancient world to work as a tool for the exchange of goods?

The factors that allowed the development of the currency as a means of exchange of goods in the ancient world were, on the one hand, the development of non-collaborative paid work and, on the other, the appreciation of various goods above the rest.

Thus, on the one hand, work ceased to have a social and community component of collaboration between individuals of the same group, to become an individual activity of own and family survival. In this way, men began to work for their own benefit, accumulating their production for their own consumption, with which the first wealth imbalances began to develop.

On the other hand, certain products (such as salt and then precious metals) began to have a higher value over the rest, breaking production parity and valuing with greater emphasis the production of these goods over the rest, using them as a representation of value and exchange currency for other assets of lesser hierarchy.