You were the one that brought up the provenance, by erroneously classififying Xinu as "new work without that history". Now you are trying to have your cake and eat it by trying to hand wave away the very thing that you yourself brought up.

Quite clearly, something from 1984 (actually earlier) is not "new work", and has a history: a history that pre-dates by half a decade even the very invention of one of the major free software copyright licences.

If you do not understand why the non-existence of the GPL at the time of first publication is relevant to the history of something being copyright licenced the way that it is, then you have a lot of computing history to learn, including all of the things that the world went through after the first publication of Xinu when it came to ideas in software copyright licencing. Xinu dates from a time when in order to run BSD one had to have an AT&T source licence.