Chasing originality is a self-defeating thing to do, but not because all worthy ideas are unoriginal. It's because it points in the wrong direction, away from the wellsprings of creativity. It's like trying to be funny. The most striking thing about all those "persistent quest[s] for originality in literature" is how utterly samey they are. Ditto for music. But then someone like Bob Dylan or Kurt Cobain does do something original, and people wake up.
The way I hear what you're saying, you found a way out of a trap for yourself (the trap of trying to be original, which just leads round in circles) by deciding that nothing's really original. That sounds like a valuable insight under the circumstances. It doesn't mean that the generalization holds universally, though (which is why you're getting objections to it here). In fact the opposite generalization might be equally true: every great idea has never exactly occurred before.
Oh, for sure, and to be fair, my response was not meant to be a rigorous logical statement, since it was in response to a jest about Sandman comics :-) However, I felt there was some truth to it so I defended it anyway.
I'm quite comfortable with the idea (original or not) that opposing concepts can both be true simultaneously. Your opposite generalisation does sound very interesting too. I'm going to write it down in my little idea notebook for further thought some day :-) Thanks!
(Thinking about it now, putting both these statements together appears like it could well need to a very interesting Borges-like story)
The way I hear what you're saying, you found a way out of a trap for yourself (the trap of trying to be original, which just leads round in circles) by deciding that nothing's really original. That sounds like a valuable insight under the circumstances. It doesn't mean that the generalization holds universally, though (which is why you're getting objections to it here). In fact the opposite generalization might be equally true: every great idea has never exactly occurred before.