The gist of the question is simple: why and wherefore the prohibitions against moneylending and charging interest ?
Longform:
Christendom notoriously held a big taboo over lending money at interest. Islam has a similar commandment. In both cases, the end result was that some minority outgroup (Jews, Romani, heretics, people adept at loopholes, Poor Fellow-knights of Christ and of the Temple of Solomon) handled whatever moneylending needed done in the community, got filthy rich as a result, got persecuted even more than your average minority in a high ignorance low tolerance setting.
But why would charging interest become such a hot potato in the first place ? I mean, nobody likes a banker of course, but then nobody likes a lawyer either and neither holy book make them anathema. I’m puzzled. Please unpuzzle me.
And as a bonus question: how did the prohibitions end ? I know it predates the loss of ground of religion as a whole in Europe, if only because I know that Renaissance Italy was choking with banking consortiums despite it being the most ostensibly Catholic place ever. For that matter, I’m sure there are banks in Dubai today as well.
So what gives ?
Back in the days before the concept of capitalism was understood, there was a perception that the only honest way to make money was to earn it. You grew crops or made handicrafts and sold them. The idea of making money from interest seemed suspicious - a little too close to theft. The general perception was that if you loaned me fifty sheckels, the fair deal was I paid you back fifty sheckels. Asking me to give you eighty sheckels in exchange for fifty sheckels made it seem like you were unfairly taking thirty sheckels from me.
And there was the social issue that borrowers usually outnumbered lenders. So you’d usually have a bunch of people who’d all owe money to one person and who’d all agree that what Nemo the Moneylender was doing was obviously unfair.
The need to borrow money is too widespread to prohibit it. As you noted, if you stop Christians or Muslims from lending money, you just end up with the Jews lending money instead.
Eventually various legal fictions made it possible for lending to be done legally. One of the main ones was fictitious currency exchanges. In Italy you had a bunch of independent municipalities so there was a bunch of different currency around. Lending money at interest was illegal but exchanging currency was not. So let’s say 100 Florins was normally worth 200 Guilders. But you and I would agree to exchange 100 Florins for 300 Guilders - with the catch that I would give you the 100 Florins today and you would give me the 300 Guilders in six months. Under the fiction of a currency exchange, we’ve just arranged a six month loan at fifty percent interest.