I think there are two primary types of death - physical and mental/social, and the existential dread this life bestows upon us naturally sends us kicking and screaming to prevent both.
As avaruus said well before, we are wired to both fear physical threats but also social, as the latter may be more abstract but also genuinely threatens our physical (and mental) survival.
On the mental side, our ego/identity is what exists, apart from our body and own lives experience itself, in society's social constructs.
I suppose, as others don't share our physical and lived experience, that is who we are to them?
What I'm trying to say is, I think the hunt for not just physical safety but also thriving beyond that may actually still derive from our survival instincts, in a way - if you are well-known, whether in your community or even beyond, if you leave things behind that are still read, used, noticed, had an impact, etc., then even beyond your physical death, your identity lives on, in a way.
"You", or, a "part" of "you", 'survived'.