Genesis is the book of beginnings. It tells of the beginning of creation, the beginning of man, the beginning of sin, and the beginning of God’s plan for the redemption of sinning man.
The first eleven chapters depict four great events: creation, the fall of man, the flood, and the Tower of Babel. From chapters 12 through 50, we see God dealing with man through four great patriarchs: Abraham, Isaac, Jacob, and Joseph. And then the book comes to a close with the children of Israel living in Egypt.
Genesis reveals to us God’s redemptive plan, as He deals with people, and especially as history leads to the messianic promises that through the line of Abraham, Isaac, and Jacob would be born the One who would save the world. So the book of Genesis introduces us to the problem—that man is sinful and can’t fellowship with God—and thus begins the story of redemption that would culminate at the cross.