I think that after death you are exactly like you were before you were born - nothing. Try imagining what you were in the time of the dinosaurs - that would be it, I think.
I would add that the presumption, regardless of how tentative, that the person continues to live after the death of the body, is an idea acquired through Natural Selection.
After eons of preference for snippets of DNA that would accumulate into the the genome we carry today, there evolved, among the elaborate network of traits, the will to survive, manifest in the rational mind.
The exact means by which a human being acquires the rational aspect of the will to survive is complex and interlaced with physiological and social causes. Clearly learning is one of the important requisites to understanding survival on a rational level.
The perfected individual, that is, after sufficient learning and physical and experiential development, will eventually converge on the rationale behind the desire to survive. At this point, reason is sufficient to conceptualize death and recognize that the finality of death poses a bind against the previously acquired will to live.
Through an iterative process, over years the wonder, the idea of death moves into a deeper awareness and may form a basis for concentrated ideation, whether through mild daydreams, meditation, or focused problems, such as whether to have a will or to make funeral arrangements.
The antagonism between the competing notions of struggling to live versus the inevitability of death will periodically reawaken the primordial urge to take evasive action to preclude the threat of extinction.
The solution to the bind, then, is to allow for the idea of death of the body, but to search for an idea that preserves an eternal mind. The solution is viable to the extent that it does not conflict with ideas that establish boundaries around the physical laws of nature, which are largely inapplicable to the immaterial nature of the mind. This may be difficult, and indeed endless.
Only by conceding certain physical laws does it become possible to imagine continuity of the being after death. In primitive culture, where availability of science is scarce or nonexistent, the determination that there is life after death is relatively easy to reach.
For the rest of us, it requires a denial of fundamental principles that we have come to understand will ultimately override every human idea.
For the above reasons, I conclude that all conceptualizations of eternal life are owed to the initial source, Natural Selection, in the manner that humans have arrived at this particular genetic configuration which codes for all the antecedent traits and behaviors that cause the idea to unfold as described.