Genesis 4 - Satan is a serpent that deceives and a lion that devours, I Peter 5:8; Revelation 12:9. He used Eve to tempt Adam and Cain to destroy Abel. Cain was "of that wicked one" 1 John 3:12, while Abel was righteous with God, Matthew 23:35.
Genesis 5 - Eight times in chapter 5 you find the sobering phrase "and he died." Death is an appointment, not an accident. Sin came into the world and through sin, death came into the world Romans 5:12. With Enoch, however, God's grace was revealed in "rapturing" Enoch to heaven.
Genesis 6 - God saw a world of people who were inwardly corrupt, outwardly violent, and upwardly rebellious. Sin spread to the whole human race and God chose to destroy those who would not turn to Him.
Genesis 7 - God was very patient and gave the world at least 120 years to be saved. The world rejected Noah's witness and suffered the consequences of a world-wide flood.