Hypothetically speaking, if Adam and Eve never sinned, but say, several generations later, someone sinned for the first time, would that have cause the fall of the human race? In other words, if Adam and Eve had resisted Satan’s temptation, would we as a race been “saved”, or would Satan have continued to tempt until someone eventually gave in to sin?
Individuals could have chosen to sin, and they would have lost their relationship with God as individuals, just as post-baptismal sin does with us, but it would not have had an effect on the entire human race in the way that it did when Adam sinned.
Now, it might have some generational effect on that person’s lineage. But the whole of humanity could not have fallen except in the first parents, namely Adam.
However, I say that only because you ask for a hypothetical speculation.
As I understand it there would have been no procreation had Adam and Eve not sinned. Procreation’s purpose was to preserve humanity, while in sin & subject to death, until Messiah could come to redeem us in the Incarnation.
Without looking it up, didn’t God say to “Be fruitful and multiply,” before the fall? Wasn’t that, as well as staying away from the tree of knowledge, essentially the first commandment?
That’s how I understand it, too. And since there was no death or sin, the human race would no doubt be populating our entire solar system, by this time.