Death and the Fall

It is an evil that we die. The badness of death is constituted by the cessation of the good of life. But not every cessation of a good is an evil. If I have a good conversation for several hours with a friend and then we go our separate ways, the cessation of the conversation isn't an evil. Only the cessation of a due good is an evil.

But how is it due to us not to die? Is it not a part of our very nature as human beings that we die?

Here's an argument:

1. If the empirical manifestation of our nature matches our real nature, what we are supposed to be, then death as such is not an evil, just a cessation of a good.
2. Death as such is an evil.
3. So, the empirical manifestation of our nature does not match our real nature, what we are supposed to be.

Claim (3) is already on its own a kind of doctrine of the Fall. And it calls out for explanation. The story of the Fall of Humankind provides such an explanation. The naturalist, on the other hand, cannot provide an explanation for (3). I think the naturalist should perhaps deny (2), but that is quite an implausible move.