I definitely get what you are saying and acknowledge that you are at least trying to make a bit of sense of the situation by trying to restrict as much possible pre-story activity to justify the PC starting at level 1.
But here's the thing from my point of view: Dwarves and elves will gain XP and level up at the exact same rate as their humans compatriots when you play the game, and their maximum levels will all be about the same throughout the course of their "adventuring" lifetime. But because dwarves and especially elves live 3 to 8 times longer than humans... by any sort of metric of what gives a character "experience"... members of those races should have 3 to 9 times more XP and 3 to 9 times more levels than any human PC.
Agreed, which is why on occasion you might encounter some truly stratospheric level numbers among stay-at-home Elves, particularly Clerics and Mages*. As a pleasant side-effect this also provides a sort-of logic behind the existence of artificers etc. capable of making and enchanting some of the stupendous magics the adventurers bump into now and then.
* - the somewhat riskier lifestyles of Warriors and Rogues mean they tend to die off before reaching ridiculous levels; and revival isn't guaranteed in my game.
It is to put blinders on to any sort of logic to think that dwarves and elves only receive "experience" during the same 40 years that humans do (humans aged 20 to 60 before they retire). Average Human adventurers get no XP for the first 20 years of their lives, XP for the next 40, then no XP for the last 20. So human adventurers receive XP and levels for approximately half of their lives. Which means average dwarf adventurers that live to 350 years old should have like 175 years of adventuring, and elves that live to 700 years should have 350 years worth of adventuring. And if they gain XP and level up just the same as humans do (which we know happens because we all play the game)... the 350 years of elven adventuring should really allow them to get up to about probably Level 180. (Level 20 for humans x 9 times as many years adventuring as a human.)
Hang on a bit here - who even among Humans adventures for 40 years? Or even 40 months, for that matter?
Most typical campaigns span just a few in-game years - maybe a decade at most if the campaign goes way long - during which time the adventurers rack up some levels. But, much like pro athletes in the real world, adventuring careers are generally very short. And in this case all the races work the same: no matter how long-lived they are it's those few adventuring years that'll put 'em on the fast track to level-bumping.
And yes, I agree that a 300-year-old Elf could easily have already had one or two or three previous such adventuring careers before this one; which takes me right back to a point I already made upthread around a need for mechanics to codify the slow decay of adventuring skills/levels over time.
But the game doesn't do that. Instead it just handwaves away the other 650 years of an elf's life wherein the elf doesn't "earn XP", just so that they can play the game along with, next to, and the same way human PCs do. Which to me... is ridiculous and stupid and I refuse to jump through hoops to try and justify in the narrative why that happens. So I don't. To me... the narrative of the story and the world have virtually nothing to do with any sort of comparison to the D&D board game.
Where to me if it doesn't all fit together somehow then the underlying point of the exercise - that being that the PCs are an integral and internally-consistent part of the setting they inhabit - is lost.
So while I agree that there's certainly some ridiculous and stupid elements here, I'm willing to jump through a few hoops if that's what it takes to make those elements explainable in a halfway-logical and sustainable manner.
But almost nothing in the board game actually "happens for real" in the story, because the D&D board game make little narrative sense. (And all we have to do is just re-read the hundreds of "What are hit points?" threads to see exactly time and time again why that's the case.)
Yeah, my take in those threads isn't always the most popular either.
