I have an analytically slightly different approach than you. I'm curious what you think about it:

First:
Simply by a the biological imprinted self-preservation instict everyone is afraid to die. That is GOOD! It gives us the ability to characterize things, situations, animals and people as dangerous before they affect us which helps us to survive. Thanks to that fear you made it so far. Yay!
And second:
When this fear though becomes an intellectual topic getting analyzed and discussed, it forms not only basic questions of what "life" and "death" is but also entire concepts based upon. And depending what culture we live in this concept varies. Some concepts reunite the departed back with the earth in form of reincarnation, others lift their souls to a new place of existence and other concepts again try to bridge between both.
Despite all different models you can summond that it includes the wish for immortality.

Now, because we express our existence as either "to be or not to be", being dead would mean "not to be" anymore - the ending of your own consciousness.
"Cogito, ergo sum"
"I think, therefore I am."
And since you cannot be aware of your first "state of being", (you just gain awareness that your existence must have had a starting point and collect memories down the road) being set in your own "being" and only experienced yourself that way, we are able to define timelines from our point of existence which we call "past", "presence" and "future". And the "future" is where the fear kicks in again. We then try to visualize us the next level of "being". Since death obviously appears to be that border everyones life runs toward to, we look for a word of what is behind that side we know, behind here and there, and call it “hereafter”.

Dying as a metamorphosis offers now two options:
The continued existence (whether in a metaphysical form or by reincarnation through another real physical being) or the absolute vanish.
With these options in mind, we are confronted inevitably with the question: "What does death look like?" And picturing "being dead" is a terrifying thought. On top of that such an abstract one that you can't put it any other way but picturing “nothing”. A "nothing" consisting any but darkness and emptiness. We cannot visualize this emptiness other than an room open to all sides.
But even this wallless space must have a starting point, a "point 0" if you will to even be capable to imagin it. And that is YOU. You in this center from which this emptyness expands.
But since death first was deterministically defined as the end of consciousness, that fear-based concept became a recursive construct, that excludes your own existence on one hand and on the other putting yourself the center of this non-existence.
It is an attempt to make a thought tangible that is not tangible. Fear awaits impossible thinking.
The hereafter is therefore a creation of an imaginable concept as a way out of a circumstance that is inconceivable.

————

However, after all debates and philosophical analyzes death remains a threattening circumstance, here is a more suitable idea for the logical-atheistic-minded that should serve as a replacement for the idea of the afterlife:

In your entire life you leave traces behind which are either from a a material or intellectual nature. Already in the pursuite of the self-realization we create things like art, writings (as this one), music and other content that leaves an impression in other people, kickstarts a discussion and lastly shapes somebodies character. And if we are just a little bit ambitious to want to enrich the lives of others in a positive way, this is an ascertained and multiplied continuation of our own existence in the world.
Neither death is of any importance nor the duration of one's own life, but only the meaning of which man is capable of giving one's own life and that of others.