@ainmosni
Money on itself is just a tool to represent value which makes it very useful for the exchange of goods and services. The classic barter suffers from the issue that offered goods and demanded goods are often not compatible for the persons involved. For example, a fisher may want to exchange fish with a baker for bread, but the baker hates fish and so wont accept fish as a payment. Money solves that issue as the baker gets money that he can use to buy whatever he wants.
Money can be seen as a unit of value for allowed ressource consumption.
Living even a modest life requires sustained ressource consumption. No way arround that without literally dying.
Humans - given reasonable external circumstances - are capable of self sustaining themselves. This is however often less efficient time and effort wise.
Simple said, someone farming 8 hours a day will produce more food in that time than someone who spends the same amount of time as a hobby farmer. Technical progress has only made this gap