And that's why copyright has exceptions for humans.
You're right copyright was the wrong tool for code but for the wrong reasons.
It shouldn't be binary. And the law should protect all work, not just creative. Either workers would come to a mutual agreement how much each contributed or the courts would decide based on estimates. Then there'd be rules about how much derivation is OK, how much requires progressively more compensation and how much the original author can plainly tell you what to do and not do with the derivative.
It's impossible to satisfy everyone but every person has a concept of fairness (it has been demonstrated even in toddlers). Many people probably even have an internally consistent theory of fairness. We should base laws on those.
> abusing the copyright laws and the patent laws have been the most significant blockers of technical progress during the last few decades
Can you give examples?
> copyrights on non-open-source programs are almost never owned by creators, but by their employers
Yes and that's another thing that's wrong with the system, employment is a form of abusive relationship because the parties are not equal. We should fix that instead of throwing out the whole system. Copyright which belongs to creators absolutely does give creators more leverage and negotiating power.