I never understood why its always written that "beastkin" live longer lives. EVERYTHING that's not human must live longer then those Mundane boring humans because its fantastical fantasy! Wow!
If you blend a wolf that lives less time then a human, and a human together, does it suddenly go higher? Apparently in fantasy! Yes because that's fantastical. Oh but they're somehow weaker combatwise and lose.
I'm of the opinion they should have "shorter" lives. Like dying at the age of 25-35, but making up for it with with faster growth rates and some levels of instinctual learning(born with some known verbal knowledge(words). This would lead to interesting societal parallels where a human might come to a town twice in their life, but the second time they come to a beastkin town, everyone and everything they've known about the towns changed. Or how the town even five years later is different in that small period.
Oh what am I saying? That's BOOOORING, they're just able to live 100 or so more years, done. More fun.
Alright, I'm done my bland, dumb, rant on fantasy world writing. I doubt anyone would agree with this anyways, I'm an idiot. At least the bit about mana affecting lifespans is a nice touch.