I reject your hypothesis that nothing would exist if copyright didn't exist.

I wonder how humanity managed for so long without it, if that were the case. Or did we just not produce art or culture until we established copyright as we know it today?

Without copyright we would probably make mostly low-cost/small-scale art, of the type that can be achieved by a single person, and probably would not make big expensive collaborative projects like $100m+ blockbuster movies which are hard to bring into existence without a strong profit motive.

thank god. what was the last $100m+ movie you watched that you thought, wow, what a great piece of entertainment and/or art?

I could certainly do without big budget MCU slop, but Lord of the Rings? I am really glad that exists.

Copyright has (for better or worse) co-evolved with the technical ability to create effectively infinite copies of works, so I don't think we have any empirical data to prove or disprove this.

Right, we have no evidence that copyright helps promote the creation and distribution of arts, culture, or technology, and yet we restrict peoples' freedom to proliferate culture and art in the defense of it.