After the Fall, the story of Adam and Eve goes on to the point you're questioning. Here's the answer:
Gen 4:1 - The man had intercourse with his wife Eve, and she conceived and gave birth to Cain...
2 She gave birth to a second child, Abel, the brother of Cain. Now Abel became a shepherd and kept flocks, while Cain tilled the soil.
3 Time passed and Cain brought some of the produce of the soil as an offering for Yahweh,
4 while Abel for his part brought the first-born of his flock and some of their fat as well. Yahweh looked with favor on Abel and his offering. But he did not look with favor on Cain and his offering, and Cain was very angry and downcast.
(Well, why shouldn't he be? Both brothers had brought forth their first fruits as offerings, but Yahveh rejected the vegetables and only accepted the blood sacrifice. This was to set a gruesome precedent:)
8 Cain said to his brother Abel, "Let us go out;" and while they were in the open country, Cain set on his brother Abel and killed him.
(Accursed and marked for fratricide),
16 Cain left the presence of Yahweh and settled in the land of Nod, east of Eden.
We can assume that the phrase "left the presence of Yahweh" implies that Yahweh is a local deity, and not omnipresent. Now Eden, according to Gen. 2:14-15, was situated at the source of the Tigris and Euphrates rivers, apparently right where Lake Van is now, in Turkey. "East of Eden," therefore, would probably be along the shores of the Caspian Sea, right in the Indo-European heartland. Cain settled in there, among the people of Nod, and married one of the women of that country. Here, for the first time, is specifically mentioned the "other people" who are not of the lineage of Adam and Eve. I.e., the Pagans.
So let's look at this story from another viewpoint: There we were, around six thousand years ago, living in our little farming communities around the Caspian Sea, in the land of Nod, when this dude with a terrible scar comes stumbling in out of the sunset. He tells us this bizarre story, about how his mother and father had been created by some god named Jahweh, and put in charge of a beautiful garden somewhere out west, and how they had gotten thrown out for disobedience after eating some of the landlord's forbidden magic fruit of enlightenment. He tells us of murdering his brother, as the god of his parents would only accept blood sacrifice, and of receiving that scar as a mark so that all would know him as a fratricide. The poor guy is really a mess psychologically, obsessed with guilt. He is also obsessively modest, insisting on wearing clothes even in the hottest summer, and he has a hard time with our penchant for skinny-dipping in the warm inland sea. He seems to believe that he is tainted by the "sin" of his parent's disobedience; that it is in his blood, somehow, and will continue to contaminate his children and his children's children. One of our healing women takes pity on the poor sucker, and marries him...
17 Cain had intercourse with his wife, and she conceived and gave birth to Enoch. He became builder of a town, and he gave the town the name of his son Enoch.
(With both of their first sons not turning out very well, Adam and Eve decided to try again):
25 Adam had intercourse with his wife, and she gave birth to a son whom she named Seth...
26 A son was also born to Seth, and he named him Enosh. This man was the first to invoke the name of Yahweh.
Now it doesn't mention here where Seth's wife came from. Another woman from Nod, possibly, or maybe someone from another neolithic community downstream in the Tigris-Euphrates valley. But her folks also, cannot be of the lineage of Adam and Eve, and must also be counted among "the other people."
But whatever happened to Adam? After all, way back there in chapter 2:17, warning Adam about the magic fruit of knowlege, Jahweh had told him that "on the day you eat of it you shall most surely die." So, when did Adam die?
Gen. 5:4 - Adam lived for eight hundred years after the birth of Seth and he became the father of sons and daughters.
5 In all, Adam lived for nine hundred and thirty years; then he died.
Hey, that's pretty good! Nine hundred and some odd years isn't bad for a man who's been told he's gonna die the next day!
Well, the story goes on. But suffice it to say that those of us who are not of Semitic descent (i.e., not of the lineage of Adam and Eve) cannot share in the Original Sin that comes with that lineage. Being that the Bible is the story of that lineage, of Adam and Eve's descendants and their special relationship with their particular god, Yahweh, it follows that this is not the story of the rest of us. We may may have been Cain's wife's people, or Seth's wife's people, or some other people over the hill and far away, but whichever people the rest of us are, as far as the Bible is concerned, we are the Other People, and so we are continually referred to throughout. Later books of the Bible are filled with admonitions to the followers of Jahweh to "learn not the ways of the Pagans..." (Jer 10:2) with detailed descriptions of exactly what it is we do, such as erect standing stones and sacred poles, worship in sacred groves and practice divination and magic. And worship the sun, moon, stars and the "Queen of Heaven." "You must not behave as they do in Egypt where once you lived; you must not behave as they do in Canaan where I am taking you. You must not follow their laws." (Lev 18:3) For Yahweh, as he so clearly emphasises, is not the god of the Pagans. We have our own lineage and our own heritage, and our tale is not told in the Bible.