I've highlighted the parts in question:
13 Cain said to the Lord, My punishment is more than I can bear. 14 Today you are driving me from the land, and I will be hidden from your presence; I will be a restless wanderer on the earth, and whoever finds me will kill me.
Here Cain is speaking as if he has seen and knows there are other people on the planet and is afraid of them.
15 But the Lord said to him, Not so; anyone who kills Cain will suffer vengeance seven times over. Then the Lord put a mark on Cain so that no one who found him would kill him. 16 So Cain went out from the Lords presence and lived in the land of Nod,[f] east of Eden.
Here, the the Lord acknowledges there are other people in the world and not only curses anyone who kills Cain but marks Cain so these other people would know not to harm him, when they found him.
17 Cain made love to his wife, and she became pregnant and gave birth to Enoch. Cain was then building a city, and he named it after his son Enoch. 18 To Enoch was born Irad, and Irad was the father of Mehujael, and Mehujael was the father of Methushael, and Methushael was the father of Lamech.
Where did Cains wife come from?
13 Cain said to the Lord, My punishment is more than I can bear. 14 Today you are driving me from the land, and I will be hidden from your presence; I will be a restless wanderer on the earth, and whoever finds me will kill me.
Here Cain is speaking as if he has seen and knows there are other people on the planet and is afraid of them.
15 But the Lord said to him, Not so; anyone who kills Cain will suffer vengeance seven times over. Then the Lord put a mark on Cain so that no one who found him would kill him. 16 So Cain went out from the Lords presence and lived in the land of Nod,[f] east of Eden.
Here, the the Lord acknowledges there are other people in the world and not only curses anyone who kills Cain but marks Cain so these other people would know not to harm him, when they found him.
17 Cain made love to his wife, and she became pregnant and gave birth to Enoch. Cain was then building a city, and he named it after his son Enoch. 18 To Enoch was born Irad, and Irad was the father of Mehujael, and Mehujael was the father of Methushael, and Methushael was the father of Lamech.
Where did Cains wife come from?