> don't the humans that fed the machine have a right to not be lost and forgotten?
Honest answer, no, not if it was publicly published and available for free, not indefinitely.
From an ethical (not legal) perspective, 18 years seems long enough for something like that to enter the public domain.
Exactly. Even the German "Urheberrecht" has a deadline (70 years afaik, outdated and too long obviously).