That's a testable hypothesis. Go sample every AI output until you find one that doesn't have a previously created 1:1 analogue.

Unless of course you mean "original" as in, some kind of wishy washy untargetable goal that's really some appeal to humanity, where any piece of information that disagrees with your hypothesis is discarded because it is unfalsifiable. Original might as well mean "Made by a human and that's it" which isn't useful at all.

Whereas I use it to mean new or different.