It’s not clear what system you’re referring to. I’m not aware of any savings and loans industry operating for thousands of years under a pure hard money system. If you’re looking for historical analogues, consider that under a gold standard, the Muslim world outlawed the payment of interest.

Investopedia

Working With Islamic Finance

The concept of risk sharing is central to Islamic banking and finance. At the same time, Islamic finance demands the avoidance of riba and gharar.

Also consider that the payment of interest mathematically requires an elastic monetary supply to function. If there are only 21 million bitcoin, how can x% more be repaid? You can’t go to a bank and borrow new units into existence. Theoretically you would have to purchase those units from holders at unknown cost, making it impossible to know the real cost of your loan from the outset.