That’s a lot of words. So, what’s the answer to the question?

If you not interested in my opinion feel free to leave at any point.

If copying is an action open to everyone, what can a person create on a computer, that they could expect other people to pay them for? What could they make that doesn’t have equal value simply to copy, than to buy from its creator?

Quite simple because you value the works of others? If you want for example a specific art piece from a specific artist you commission it from that artist. We also don't need to have a theoretical debate about it - since steam exist. You can have most games pirated or get them even cheaper (than on stem) from grey key market - but if one makes a convenient affordable (localized cost for example )distribution options, people will pay for things they use - because most people actually think that it's the right thing to do (as long as they can afford it). No everyone is an asshole, most people are actually not.