Philosophers - or indeed authors more generally - who assume that this mortal life (bounded by conception and death) is the unit of meaning; always fall into one of two categories.
The optimists say that real life is 'life at its best', the bad stuff is due to wrong persepective, wrong choices; and our problem is that the best is infequent, does not last, or may be absent.
The pessimists (more common) assert that real life is 'life at worst' - i.e. the reality is suffering, disease, decay... And that the best bits of living are ultimately evanescent illusions - wishful-thinking, self-deception; a personal delusion, a temporary mania...
The two attempted escapes from this, are either to assert ultimate one-ness - which attempts to remove the difference between the good and bad bits, by removing individual awareness of that discernment. Or else, versions of 'living in the moment' - which (in effect) say that the instantaneous moment is the true unit of life. Life is therefore static; and whatever is in the moment is everything.
(This collapses when one moment changes to another - then what? Or when the moment is bad and there is no counterbalance or context for its badness - e.g. pain is totality.)
My conclusion is that there is no possible coherence attainable when the unit of life is regarded as being bounded by conception and death. Because what meaning and purpose in my life is possible when my life (and every life) is temporary and inevitably ends in death?
Life and living is then finite; death and nothingness the only infinite.
But this point can be generalised. If all individual lives converge on the same identical outcome, then there can be no meaning to those individual lives. An assumption of convergence is itself lethal to meaning.
If all human lives end-up in the same and identical state of anything (whether bliss or suffering or nothingness); then individual life has no meaning. Indeed individuality is then a problem - The Problem.
Conversely put; if we all end-up the same (and if that situation is eternal) then the only situation that could provide meaning and purpose to my own individual life; would be if individual lives lead to unique outcomes...
This problem of convergence onto a common end-state seems to be something I observe in many atheists, many religions and spiritual belief systems, and among many Christians (who seem to regard their anticipated life in Heaven in terms of some kind of de-differentiated glowing sexless angel, ecstatically praising God with music and chanting, forever - in an unchanging situation beyond time).
Obviously I am being hyperbolic and mocking; but some such convergence of outcome, some such definition of Heaven in terms of negation, seems common among self-identified Christians through history, especially of the intellectual sort.
And such convergence is lethal to meaning in our own mortal life. Indeed such Christians often have a theology that itself converges-onto 'Eastern Religions' of a deistic type, with this life as maya (illusion), and the-self (with its mortal attachment) being seen as the enemy, and dissolving of all individuality into unity...
In sum: If my life converges eternally with other lives to any common end; then my mortal life is futile - because everything that is me is washed-away, and what remains is depersonalised.
(The individual self is a mere changing blink in time, and the 'me' that remains eternal has nothing uniquely 'me' about it.)
Take it a step further - if the-above, then there is no point in me existing in the first place.
Why bother having me-personally, or any other individual persons; if they are just going to be washed-away by convergence-onto some common outcome?
No point. We might as well (should have) gone directly to the final and eternal state... without any of this tedious and mucking-about in mortal life.
(Mortal life would be deleted, and existence would be like a Go To Jail card: "Go to eternity; go directly to eternity; do not pass mortal life; do not collect 200 pounds.")
My conclusion is that for my actual mortal life (this life) to have genuine meaning and purpose; then my eternal destiny (the situation I end-up-in forever) must be unique to me.
If this is indeed so, then God's main problem is to make an eternal Heaven from a bunch of unique individuals.
And this is just what Jesus Christ, and the resurrection he brought, is all about: enabling each of us to become an unique individual, who can live eternally together with other unique individuals, in Heaven.