Read Genesis 5:1-32.
Verses 1-5 set off this chapter from the last in that this is the “book” of the generations of Adam. The Hebrew word for Adam is the same word translated as man in verse 2 (‘adam). God created mankind into two sexes: male and female. There is no biblical support for any other distinction.
Chapter 5 follows the line of Seth, and declares that Seth was made in Adam’s own likeness and image. In so doing it reminds the reader of the thought that Adam was made in God’s likeness. In this sense the line of Seth was closer to the image of God than the line of Cain, which had distorted the image of God in their further rebellion.
In reading this chapter you quickly notice the longevity of the persons listed. Some have argued that, like the Sumerian King List (which mentions kings of who reigned before the flood living 28,000 plus years), the ages are merely symbolic in some way. This interpretation has no ground biblically though, especially in light of God’s statement that he would shorten the life of humans to 120 years in Gen. 6:3. It is possible that some generations were skipped and that this was not a comprehensive list, as the word “fathered” in a genealogy can mean “fathered an ancestor of.”
The pattern of this chapter is: name, years lived until the man fathered someone, years lived after that, followed by the total amount of years lived. However, Enoch’s record, in verses 21-24, is in stark contrast stating that he “walked with God” and “was not.” Indicating that Enoch did not die a natural death as the others.
By faith Enoch was taken away so that he did not see death, “and was not found, because God had taken him”; for before he was taken he had this testimony, that he pleased God. [Heb 11:5 NKJV]
The Lamech of verse 28 is a different Lamech than Chapter 4, in that this Lamech was of the line of Seth and the other of the line of Cain. It is interesting that this Lamech speaks of a blessing that his son Noah would bring (comfort and relief) while the other Lamech spoke of a curse. The contrast is no doubt intentional, to bring attention that those who walk with God bring blessing and those who do not bring cursing. The years of Lamech, 777, also indicate completeness, wholeness, and holiness. That age was coming to an end, and Noah would bring in a new age (post-flood) which would be a relief and rest compared to what they had been living with.
Chapter 6 will demonstrate just how far mankind had fallen, and Noah would be an instrument of salvation through the flood of God’s judgment. In this, Noah would fulfill the prophecy of his father Lamech. It is interesting to speculate how difficult farming would be pre-flood since the earth was watered by a mist, and there was no rain as of yet. Following the flood rain would begin to fall. Rain is an extremely important aspect to agriculture, especially in ancient agrarian societies. Perhaps after Noah the land would be easier to work due to rainfall than it was pre-flood.
Walking with God brings blessing, while not walking with God brings cursing. I want to know God like Enoch knew God. And why can’t I? Perhaps I can know God even better, now that Christ has paid for my sins and the separation of sin is removed as far as the east is from the west.
Enoch is a mystery. We know that he was some sort of prophet (Jude 1:14-15), who announced the coming judgment of God. And yet he was spared from that judgment, because he walked with God. To those Christians that live in the last days, no doubt they will be like Enoch. Walking with God in one moment, warning of God’s coming judgment of the second coming of Christ, and subsequently caught up to meet Christ in the sky (1 Thes. 4:15-18).
This should be a comfort to you, and an encouragement to walk with God closely even if the world around you is falling deeper and deeper into sin.
 ESV Study Bible: Commentary Notes on Gen. 5:1-32.