One of my favorite subjects
It is even worse than that. There is no "actual money" at all. It is all debt in one form or another. Even the central bank money is still a debt, IOU-bill that promises that with that bill you can get goods and services, or other sort of money. However, government issued money is a very reliable source of goods and services, because the government can force by gunpoint goods and service producers to give you goods and services for your money. This is about the only thing that makes the central bank money more real than a money, aka debt notes, issued by a Smallville's Local Bank, which can't support the trust to its money, aka debt notes, same way. Actually, this trust issue was one of many reasons why physical money of other than government mints was eventually forbidden - to protect people from scams and very untrustworthy local currencies.
While it wasn't intentionally designed to be like that (in ancient times), it has evolved to be like that for a very practical reason: To keep the economy running and to motivate you to spend your cash rather than to sit on it. You buy something now, because it will be more expensive tomorrow, and this way create the demand, which creates the motivation to offer the supply, and which creates the employment. All this to happen now, creating wealth (not only money, items, standard of living etc.) to the society (all levels of it) today instead tomorrow. Also, it motivates to invest to the enterprises that create goods, services and more money thru the interest.
The problem: To keep the standard of living increasing, the system requires increasing consumption of goods and services, resulting without equal technological advancements increasing consumption of finite natural resources. Not to mention, that without the society's intervention the only way (that I know) to ensure that the wealth would distribute equally, would be that all people would be equally skilled and informed in handling money, and that all people would be in the equal position in the society and in the life situation.