In the beginning, human civilization could not imagine trading something that was neither useful nor could be eaten for anything else useful or edible. We had only the barter system. If it wasn't useful or edible it was of no value.
Around 3000 B.C., humans started using objects such as gold as a tradable currency. In the 7th century in China, and 17th century in Europe, we started using paper currency. By 1971, in the United States paper currency (fiat) was no longer based on gold - became simply backed by the strength of the government.
And now we have crypto, neither useful nor edible, whose value is based on supply and demand, at its core, much the same as fiat.