There are a few points that I disagree with your contention.

First, paper money was introduced in order to have an internationally recognized currency which can be use as the main medium on a respective country for reasons of trading, investing, and lending. If we were still to adapt the barter system of payments, there would be no means of knowing the actual value of a thing since everything revolves around trading goods.

Second, interest rates are created by the banks in order to take opportunity of the time. While the rates may be relatively low, the chances are guaranteed since the security that most banks give are based on the fiduciary relationship created between the depositor and the bank.

Third and final point, without the fiat system, the world would be in chaos with regard to trading and investing.