I am having some involuntary doubts about the Fall account.
as I understand it, Adam and Eve are two historical persons to whom we are all related, and their fall caused the death and disorder of the natural world
That is correct catholic teaching. The encyclical on origin of the humans says that Catholics are not free to believe in polygenism for the reason that the pope at that time was unable to find a way to reconcile the doctrine of Original sin with other theories of the development of man.
In the NAB bible, the book of Tobit chapter 8, which is taken to be 2nd canon, there is the statement that “you made Adam and Eve; and from these two the human race descended”
usccb.org/nab/bible/tobit/tobit8.htm
However, when I look at my Greek copy – as the book of Tobit is not found in hebrew – it is found in a different verse number – eg:6.
But it unmistakably says “εκ τουτων εγενηθη το ανθρωπων” – out of these, came to be mankind offspring.
So, In any event, other scriptural books treat Adam as a single human figure from whom the whole race descended in a consistent fashion w/ church teaching.
but humans didn’t even exist for most of evolutionary history, which involves much death
That is correct, and even in the book of Genesis – Man was made last, at the end of the seven days of creation. (not literal days.). The entire earth awaited him to tend it, and put it in order.
That death existed before – is not really a problem. God said to Adam that the fruit was to be his food – therefore, it is clear that the fruit had to die in order for Adam to eat it. Not only that, God in proclaiming the fertility of the natural world spoke about the seeds inside fruit causing the reproduction – hence, Jesus’ statement about what a seed is to do (die) in order to bear fruit is what you need to look at carefully:
Unless a seed fall into the ground and die, it remains but a single grain – but if it die, it will yield a rich harvest.
This isn’t the death of the curse that God threatens Adam with – for that is “die to death” – eg: a double death. It goes even beyond the death of his seed which is required for fertility of his wife. The blessing of fertility includes a self sacrifice (no matter how small it may seem to us now.)
*Immortality *is a result of God’s friendship. Jesus himself says “I am the resurrection”.
Adam and Eve could not loose control of their body to death and decay for as long as God was with them; He made up for their necessary deficiencies. This is the same that will occur in Heaven – Jesus will make up for our necessary deficiencies allowing us to live eternally.
I don’t know exactly what paradise was supposed to be for Adam and Eve if they had not sinned. What it means that the world fell with them is something that Evolution, or even the Fossil record without Evolution, requires us to consider very carefully.
Peace of Christ.