You know, I was watching Voyager Flashback and ...
I take it you haven't seen the Enterprise episode "Regeneration", where Captain Archer fights the Borg 200 years before "Q Who"?
But at the time of Q-who, Picard and the Enterprise E hadn't yet traveled back in time.
And Borg wreckage hadn't been dumped in Antarctic.
And historically Lily was probably aboard the phoenix warp flight.
And historically the NX-01 wasn't named "Enterprise."
And the NX-01 never encountered the Borg during it's voyages.
When Picard and crew were in the 21st century (FC) their actions and those of the Borg changed history. But there was a original unaltered
history prior to those changes.
At the time of Q-who, the original history was still in place
Or maybe there was the Borg wreckage and all the other stuff, because Picard and his crew had no choice but to do what they did?