With this topic I propose an improved version of my previous explanation to discussion in the Forum.
The improved explanation can be summarized with the following statement:
God created the world since the beginning at the Big Bang as if the first human sin had already happened, but created humankind in the image of God at the Neolithic as if the first human sin had not yet happened.
Physical death, illness, aging, and the selfish Darwinian mechanisms that underpin evolution are part of the state of decay inherent to creation since the Big Bang. They are in particular encoded in the DNA and become transmitted through reproduction. It is the state of “frustration and bondage to decay” referred to in Romans 8:20-21.
On the one hand, this state is foreseen by God in case humans sin, for the sake of facilitating the conversion of sinners (as suggested in Romans 5:12-21).
On the other hand, God could not become himself the cause of temptation, and consequently God created the human beings in the image of God in a state of “original grace” such that the decay and frustration (present in the rest of creation) was nullified: The first humans in the image of God were not submitted to death, illness or aging, and did not fill any selfish tendency coming from the flesh (the “thorn in the flesh” in 2 Corinthians 12:7-9). This is the state of “the garden in Eden” referred to in Genesis 2:8, also called “original state of holiness and justice”.
After the first human sin, the human beings in the image of God lost the original grace they had in the garden in Eden, and therefore the state of decay and selfishness of creation encoded in the Homo sapiens DNA prevailed. And God bounded everyone over to this state so that he may have mercy on us all (Romans 11:32): Humans became submitted to suffering through death, illness and aging; the selfish evolutionary tendencies degenerate into “concupiscence”, which opposes the commandment of love and became transmitted concomitantly with the Homo sapiens DNA. This state resulting from the prevalence of selfish evolutionary mechanisms in absence of original grace is the state of original sin.
Thus, the first sinner (no matter who he was and when he sinned) is obviously a real character, and can be considered the progenitor of all humans coming into existence in the state of original sin, as the first sin is the cause of the state of deterioration of creation, and this state becomes transmitted with the Homo sapiens DNA: “Sin entered the world through one man” (Romans 5:12). In this sense, the reason for the transmission of “the state of original sin” is a theological-biological one.
In summary, in creating the world God takes into account the option that “humans sin” and the option that “humans do not sin”, and makes a world that is good in either case.
Thanks in advance for any comment.