It doesn’t all have to make sense either. How can Aravi be in Skyrim when the events of that game happen 200 years in the future from the events in Oblivion? They can’t really, so I ignore that little detail.
I always wondered this but you pretty much cleared it in your Aravi thread. I'm totally the opposite. I MUST come up with reasons my characters live that long otherwise I'll beat myself over it

Dragon Breaks.
Daedric Interference.
Vampirism.
Corpus 'Curse/Blessing'
Telvanni Magicks.
CHIM.
I could go on.
Vampirism and Lycanthropy and Daedric interference mostly. The rest are, eh, a real head-scratcher.