Was the crunch caused by mass defaults on assets worth far less than the loan value? Or was the money the banks were lending out in reality not backed by deposits but rather really and truly 'created out of thin air'?
I don't know how many times I can say it, or how many different ways I can say it, but commercial banks cannot create money out of thin air
I know it might seem like an attractive rhetorical critique in the era of the soundbite, but it's a baseless & inaccurate. Your far better to understand how the wider system works as there's plenty in it to critique that's just as biting and hard hitting, and is actually true, as opposed to this 'out of thin air' stuff.
Think about it for a minute, if banks could create money out of thin air - why would there be a banking crisis at all? The first big tangible collapse in the UK as a result of the crisis was Northern Rock going under. The direct cause of this was not because of bad debts, but because they were unable to fund their ongoing operations in the money markets , i.e. they weren't able to borrow enough money from the markets to continue (compounded by a run on the bank with its customers withdrawing money from it). If commercial banks could just create money out of 'thin air' why didn't they just do this to survive? Why did it matter that both individual customers were taking their deposits away from it and the domestic & international money markets were refusing to lend to it? Why did it have to rely on things external to it if it could just create money out of thin air? The answer is of course that they can't do that. As previously said, the banks are not the independent driver/variable in all of this
If you want to borrow money from a bank, the bank can provide that money in three ways:-
i) it can use existing money coming into it from repaid loans, interest on existing loans, or customer deposits to fund the loan
ii) it can sell existing assets to convert them into cash to fund the loan (this general manner also covers new central bank base money coming into the system, as that's the way it enters the system) - but it must sell them at a level that doesn't cause it undue losses
iii) it can borrow from the domestic or international money markets, and then lend that money on
There's no 4th option where they can create money out of thin air - all three things above depend on someone else, somewhere else, doing something, that then allows a bank to lend
Kabbes has covered the point about the crisis - but in short, it's because value generation didn't match up with (fictitious) capital circulation and because of that, the latter had to be destroyed to reestablish value relations. lending in itself doesn't tell you much about the system, what's important is whether the money that starts circulating as a result of that loan ultimately takes part in value production somewhere else - if it does then things can hobble on, if not then crisis will intervene.
This is why I thought your initial hypothesis in the OP was daft & pointless - you were looking at the wrong driver (interest rates) to explain the wrong thing (inflation). You need to go deeper and actually think about, and understand, money and value - before looking at the effects of those things and their relationship with each other