Huh? What does interest have to do with inflation?
If I loan you $50, and ask for 10% interest, you must pay be $55. That $5 comes from somewhere. In a physical money economy, that literally means it comes out of someone's pocket in some way (starting a business etc.). You can imagine that if we have many many loans overlapping, over long periods, we might begin to have a money deficit.
To be honest, I don't have the proper expertise to explain it perfectly. But I hope that it gives an intuition.
No. the interest is just a claim on part of real production. Creditors would buy some products or services from debtors and that is where $5 came from.
https://www.cato.org/policy-report/julyaugust-2011/deficits-...
(I realise limiting the money in circulation to $52 is an absurd formulation, but using these crazy limits helps understand the larger system)
The difference between real growth and the amount of currency is the "metabolism" I referred to earlier.
First, central banks usually send any profit they make to their governments. (See eg https://www.google.com/search?q=fed+profits+to+treasury for lots of examples.) The governments then spend the money. There's no endless accumulation.
Second, there were long stretches of time in the past when inflation was zero or even negative. Have a look at the so called 'Long Depression', a period of rapid productivity growth in the latter part of the 19th century. Just look electronics usually fall in price these days, almost everything slowly fell in price back then over long periods of time.
But banks were just as 'evil' as they are now, and people paid interest.
Third, money doesn't have to be based on debt, either.
Historically money based on commodities was common. But in Japan their central bank recently bought stocks in return for newly 'printed' money. There's no obligation on anyone to ever buy the stocks back from the central bank.