I fully agree that it feels wrong and weird that you would give your money to a bank and get less money back later. But if I stop and think a bit further, that feeling starts to feel less and less justified. Here are a couple of reasons:

1. We talk about nominal values, not real purchase power. You should not care what is the number on your bank account but how many apples you can buy it. And with that measure, banks have been "stealing" your purchase power almost always. (Actually I think it is impossible in the long term to have banks pay more than inflation rate)

2. Assuming you save 100 dollars and expect to have 101 dollars in one year's time, central bank can decide to lower the interest rates so that you have less than 101 dollars one year later. Why would central bank "taking" from your 101 to 100 be any less stealing than from 100 to 99?

3. Finally, you agreeing to lend your money to the bank with whatever interest rate bank offers is completely voluntary action from your side. Not only you can choose to consume the money immediately, there are also practically limitless other opportunities to invest (or "invest"...) your money. Corporate debt, real estate, equity, cryptocurrency, gold, commodities etc. Now, of course, you can argue that these other options are somehow less practical or more risky in certain ways, and that society needs to keep your hand and guarantee you a risk-free and practical way to move your consumption decisions over time. And that society needs to make this guarantee to you completely regardless of the welfare cost (unemployment, recessions etc) delivering this guarantee has. At this point, my nose is starting to detect the repulsive smell of socialism, totalitarianism or something like that...