(I haven't read the campaign specific information; perhaps I'll come back to it. My reply is generic.)

For humans: you've got a source, so if you find it credible use it. Unless the average folk have access to healing and curing magic, in which case increase lifespan accordingly; a little if access is spare, a lot if access is copious.

Elves (and other long lived races) are trickier. If they have the same vulnerability to disease, starvation, and violence as humans then they should die off at about the same rate in deaths per capita per year. But that would just make living to their racial maximum ages very, very uncommon and give a real average lifespan barely longer than humans. Using the same fractions of racial lifespans as humans achieve would seem to make sense, but they need a correspondingly better ability to avoid early death by assorted causes. That's not too hard in their traditional environments, but you might say that elves who move to human dominated cities end up having human-like life expectancies. On the third hand, since elves mature slower, roughly proportionally to their racial life spans, dying at human ages would mean that practically no city elf lives to adulthood. So I guess they need super-human disease resistance and accident survivability. Or perhaps this is something best not examined too closely.