We also see as we go through, that the punishment gets worse in a way - people get further and further away from the Garden situation. Adam's punishment was to till the ground in painful toil. He was driven from Eden to the ground outside. This promise is to be the focus of the rest of the Old Testament in a way - waiting for the One to be born. Genesis puts a high emphasis on birth.
Birth is often the occasion of prophecy.
Imagine reading Genesis as a story, without having read any of the Bible before. We have the promise of Genesis 3, that one would be born, the seed of the woman, who would crush the evil serpent's head. The promise is to the snake, by the way, but it is nevertheless a promise to the woman also. It is a promise that humankind will continue - a seed, an offspring will be born. And when we get to chapter 4 that promise seems about to be fulfilled.