The gulf between how-we-actually-are and what-we-know-we-should-be is vast - but the response to this fact has been very varied.
Clearly, most people accomplish very little in terms of perfecting themselves throughout mortal life (and the great majority of humans who ever lived rapidly died in the womb soon after conception, or shortly afterwards as young children).
If Men are to bridge the gap between actuality and perfection, it needs something else; such as multiple accumulative lives (i.e some kind of reincarnation), a once-for-all infusion of divine help during or just after mortal life and before resurrection, or (as I believe) continued spiritual progression after resurrection and through eternity.
Mortal life has considerable scope for spiritual progression, but lives differ hugely in terms of length and experiences; so if mortal life has an important role to play then it seems to suggest that there must be some kind of matching process by which a specific soul is placed in a specific situation where he or she is best able to have the necessary experience, and has the chance to make the necessary choices.
In other words, the implication is that this life you have, or I have, is in broad terms the life our souls needed in order to learn some particular thing (or things) of great importance.
This is not the only, nor is it the primary, benefit of being born into a mortal body and dying - the primary benefit - the main instrument of spiritual progression - comes from simply that: incarnation and death.
But the fact that some people (like ourselves) have a long life also has a meaning, albeit a secondary meaning - it may suggest that we have something important to learn (that we had something we specifically needed to learn, some aspect in which our pre-mortal souls were deficient) - so that long life was not our reward, but merely a functional necessity (or at least a potential benefit) for our particular souls.
(This also implies that many of those men and women who died in the womb or as babies really are better - fundamentally - than those who survive. Of course, some of these were not intended to die and their lives were cut-short; but almost certainly some were intended to die soon after incarnation - because their souls were sufficiently perfect that they did not need to undergo the spiritual trials and risks of extended mortal life.)
If we long-lived have failed to learn the specific lesson/s of mortal life - what then?
Some would say we reincarnate and try again; but Christian revelation seems to regard reincarnation as very exceptional, and not done for this kind of reason.
Therefore, I suspect that if we mess-up our chance to fix the deficit in our souls during mortal life, it means that we are placed in (i.e. we are suitable for) a lower level of Heaven - which means that our spiritual progression is slowed-up considerably.
Slowed-up, and perhaps slowed up for large periods of time which must be lived-through; but progression is presumably not thwarted forever.
Since our loving Father made creation for our spiritual progression, and since we personally chose to undergo mortality (we could have remained unincarnated spirits, and stayed in Heaven); and since there is eternity for the purpose; it seems reasonable to assume that mortal life is divided into two benefits: qualitative and quantitative:
The qualitative benefit of mortal life - which all receive (except those who specifically choose to reject it - God does not force benefits upon us, He does not want to and indeed He cannot) is the incarnation into a body and death of that body then its resurrection - a process which all Men undergo.
This moves us to a higher level of spiritual being - when incarnated we have become higher beings, more divine than our pre-mortal selves, more perfect, closer to God-nature.
The quantitative benefit of mortal life is the chance to fix particular spiritual problems by our choices and endeavor through mortal life.
If this goes well, if we make the right choices and proper efforts, then after resurrection we will find ourselves better (significantly more 'perfect') people than if we make wrong choices and have led wrongly-directed lives.
Better lives lead to acceleration to a higher Heaven, better able to participate more fully in the eternal divine work of love and creation.
Worse lives presumably lead to a minimal salvation in one of the lower mansions of Heaven, in which (compared with our pre-mortal selves) we have become 'lower forms of higher beings': higher beings because now we have bodies (are incarnate), but at a lower spiritual level than we started out because of our misdirected mortal lives.
Of course we might choose to stay that way (such Heaven is, after all, bliss compared with mortal life; which is one reason we chose to take the risk of undergoing mortality) - but over eternity most will repent the bad choices of mortality and want to progress.
It seems natural to assume that our loving Father would not thwart any desire for post-mortal spiritual progression. So, unless post-mortal spiritual progression is for some reason utterly impossible, I think we must also assume that spiritual progression in the post-mortal life must be a slower and more difficult thing than during mortal life - otherwise, why would we bother to experience prolonged mortal lives? Why would we not not just incarnate and die straightway, and thereby avoid the potential for choosing damnation?
The lesson for the longaevous Men, for you and I, is that we are here, here-and-now, for a reason or for several reasons; and that our main job is to to try and make the best choices and try to live with the best motives starting from exactly this situation.
A long mortal life is not a reward, but a task; so long as we remain alive, our task remains undone, incomplete, significant soul-problems still need to be fixed.
We (you and me, nobody else) have this responsibility (although there is much help for us, if we ask for it). There is no cop-out; and our decisions will necessarily have very significant and lasting consequences - we will have to live with the consequences of our decisions.