I very much agree with your general point but still feel 20 is too short. / Somewhere in the 30-50 range.

Copyright is not the same as patents nor is innovation the only or necessarily the most relevant concern.

Authors have rights, especially artists are often not immediately discovered, and a lot of large businesses would be able to suppress new works for 20 years.

This shows ignorance on how creators make money. Creators don't make money purely through producing new works, per se. They create money with a robust set of works whose long tail collectively forms enough money for them to live off of. This relies on the notion that the intellectual property of the creator is theirs for a significantly long time. This is because the money made upfront is unpredictable [a novel's upfront payment is often just a few thousand dollars, but takes over a year to write, edit, and produce...]

The "long tail" of works makes practically zero money. Most of them simply go out of print and into a copyright-induced memory hole. Works that still make money decades after their creation are quite exceptional.

This is only true in the sense that all creative people are generally paid exceptionally little for their work, and make practically zero money. But of those that do make a living, it is through having a robust and regularly selling body of work that is still paying money years or decades later.

This is also partially why royalties were a huge fight against Disney a little while ago, when Disney started to refuse to pay royalties for Star Wars and Marvel works after acquiring the companies that owned them. Those works were still selling years/decades after their original creation and those creatives were still owed that money.

So we should subject all works to extreme copyright lengths on the mere off-chance that a tiny fraction of them might still be making appreciable amounts of money decades later? Looks like a total non-starter.

No, I'm saying 20 years is too short because it destroys the livelihoods of the already-few creatives who can make a living off of their work, because 20 years is based off of a completely ignorant idea of how creatives earn livings.

20-years is nothing in the terms of the life span something. If you look at a lot of the authors they spend their lifes writing. Just like you'll spend more than 20-years working, so will they. But it seems you want to hamstright their earning rights. To me it's absolute greed and stealing from the working man.

The entire point of allowing things to go public domain is they is no need for copyright protection anylonger. But if people are still earning their living off of that work then someone would be getting hurt.

And this talk of a total non-starter. You need to explain why 20-years is enough. Because it's 100+ just now. So you're the one on a total non-starter.