Consider what we used as currency before it was currency. You would have to barter before, which was inefficient. Common currency saves you and everyone involved time. Instead of having to barter for every item, which would also require you to do carry all of those items, you can just pay with currency now.

We can think of it as a universal language for trading. It doesn’t matter what item you eventually want, you can trade money to get it.

Extropolating, want, or greed, is what gives money its value?