This is the book of the generations of Adam (KJV). We have a correlation between Genesis 5 and Mattityahu 1:1-17. Both sections start out by saying: This is the book of the generations of. These are the only two places in the Bible where this is true. Moreover, we notice that the genealogy of Noah is followed by the story of Noah. And the genealogy of Jesus is followed by the story of Jesus. Thus Genesis tells of the origins of the first Adam and Matthew speaks of the origins of the last Adam (First Corinthians 15:45).92
When God created (bara) man out of nothing, He made him in the likeness of God (5:1).Both of these words take us back to day six of the creation account where God created man in His own image (1:27a). Or as it says here: He made him in the likeness of God. This written account is concerned with the passing down of the likeness of God through ten generations.
He created them male and female and blessed them (5:2a). God’s blessing of His image at creation cannot be missed: male and female He created them, and God blessed them (1:27b-28a). But with that in mind, the rest of chapter five traces the result of sin, which is death - physical death and spiritual death.
And when they (plural) were created, the LORD named them (plural) manormankind(singular). It is interesting to realize that the word Adam and man both come from the same Hebrew word. The context determines which word is used. Notice the switch from the plural to the singular. Here the word is not used so much as a proper name of the first man, but in the sense of humanity, or mankind (5:2b).