There is no direct evidence for any spiritual existence beyond death. As far as I know, all theories about any spiritual pre-existence are based on faith or philosophy. Past life memories can also be explained philosophically, particularly in light of quantum theory, which essentially says that all possibilities happen simultaneously through an infinite multiverse.
So, what can be deduced from observed phenomena?
Apparently, I see beyond the common illusions of our shared Reality. This perception implies a meta-Reality of some kind, which to me seems more reasonable and consistent than the beliefs I inherited through genes and environment. Therefore, at least for me, the ideas of reason and consistency must transcend perceived experience. If Transcendence is an aspect of Reality, then a self-aware Identity must encompass and define the Reality. Such a meta-Identity may well include me along with everyone and everything else. My immediate identity is determined by my own self-expression and the continued awareness of my social environment. After death, my own singular identity will no longer be able to express itself in the inner ways that define me, and eventually the relationship connections that maintain my outer definition will cease to have any meaning. I have faith that if this is true, then the meta-Identity will continue to be aware of having lived my life, along with all else.
I think the whole point of our individual awarenesses is the self-expression of the meta-Identity, whose own reason for existence is for the continuance of the meta-meta-Identity, and so on. The only way to avoid the thought that nothing we do has any persistent value is to remain focused on the moment, adopting certain ideals of faith that allow the greatest success in navigating our individual journeys. It has been my experience that Life rewards those who learn its ways. Ultimately, if our ideal goal is to find the means of expression that best define us, success not only improves the journey, but also serves the ideals of the meta-Identity.
I used to say "Be Here Now," but that phrase seems so static in light of the above. A better ideal to adopt may be, "Success through enlightened dynamic self-expression".