Does this inference of yours assume that Humanity would have legal standing as though it were a global corporation or government? Everyone would have to agree to belong to that abstract entity that pays out all of this money. Would Humanity Inc have spokespeople? A CEO perhaps or a president? What would stop them from being corrupted by their awesome power?

I'm just playing devil's advocate here and trying to understand the scenario. You write as if the global lending and borrowing would be automated, as though it were dictated by a law of nature. A legal infrastructure would have to be in place to tell banks to give everyone their share of Humanity's money. So we'd have to come together as a species, no? That might be a tall order.