Honestly I'm not sure what you're here to argue about.

You keep wanting to assume that banks have to make loans and pay interest.  And I'm telling you that this is emperically false.  It's not even the way banks operate today.  Go sign up for a savings account.  See how much interest you get.  Apply for an unsecured loan.  See if you get one.

Banks today operate by enabling trade, not savings or investment.