I think we're making very similar points,essentially that the numeric "interest" up at the top is not some abstract trick of accountants to pay each other with the government's help. It's an actual representation of real value being created by and for the individuals in an economy. My angle on this is "Warren Buffet's 5% interest isn't a scam, it's 5% more people having food and houses". You angle seems to be "I imagine a model in which people stop building houses and growing food and the whole thing collapses and Warren Buffet can't keep getting his 5%". I don't exactly disagree, but most of your assertions are question begging.
"If it's not decoupled from zero-sum, then it's not really creation." Well yes, but it is decoupled from zero-sum, that's the whole point.
"If we model the whole thing as a box with inputs and outputs, you need infinite inputs to get infinite outputs". Well yes, but that's thermodynamics. It's essentially axiomatic, but it says more about your model than about the real life system you're modeling.
"Value" isn't finite - or I suppose everything in the universe is finite, but many things are so vast as to be orders of magnitude larger than we need for any practical purposes. If we define a system that values only gold, then yes, we're going to run out. If we change the system to value only oil, then yes, we're going to run out.
But again, the merit of the system here is that it values whatever humanity values, and that changes as humanity changes. If it were an argument, you'd accuse your opponent of moving the goal posts and scoff, but it's not an argument. It's life on Earth, and the goalposts are supposed to move.
If you look back at historic economic analysis like Malthus, there was a genuine concern that we were headed to a crash because of finite land and wood. In order to provide heat and energy we needed forests to provide wood, and in order to grow food we needed to cut down the forests and use the land, ergo we're doomed. But then we discovered oil. And fertilizers. And GM crops. And solar and wind and natural gas...
Again, he wasn't wrong that in an abstract way everything is finite, but his model - necessarily - didn't include things he didn't yet know about. Your model tries to reduce everything to "raw materials" and "labor". But not all "raw materials" are created equally, and many are renewable or recyclable, and new sources and new materials are continually discovered. If you narrow the model to focus on one thing at a time, then you'll find it to be dangerously finite, but society gets to adapt and change what it values. For example a vast amount of resources today are spent on entertainment. Surely you don't intend to tell me that's a scarce resource that our all-growth economy will deplete?
The same goes for labor itself. If you treat Labor as a big undifferentiated blob, it makes it easier to model, but if I created something that suddenly transformed 100 Million "unskilled laborers" into workers with PhD level education and 10 years of experience in some field, that would have actual economic value. Which is why people pay for those things. But in a "resources and labor" model, at best it makes the labor blob bigger.