Shared ground
Genesis 5:1–2 works like a title and opening summary for the genealogy that follows. It signals that what comes next is an organized “record” of Adam’s line (“the book of the generations of Adam”). It also ties that record back to the creation of humanity: God created the human in God’s likeness, created “them” as male and female, blessed them, and gave them the shared name “Adam” on the day they were created.
The passage repeats earlier creation themes rather than adding new storyline details. It frames the coming list of names and lifespans as part of the same human story that began at creation, not as an unrelated family tree (compare Genesis 1:27).
Where interpretation differs (only where needed)
Some readers think “the book” implies an actual written document (or source material) behind the genealogy; others think it mainly functions as a formal heading meaning “here begins the official record,” without requiring a claim about earlier paperwork.
Some readers take “Adam” here mostly as a personal name for one man; others emphasize that “Adam” can also mean “the human / humankind,” so “called their name Adam” highlights a shared human identity (male and female together) even while the genealogy will trace one family line.
Some readers take “in the day” as a literal 24-hour day; others treat it as a Hebrew way of saying “when,” pointing to the creation event as the reference point, not necessarily defining the duration.
Why the disagreement exists
The text uses compact, traditional wording. “Book” can mean a written scroll, but it can also be a conventional label for a structured section. “Adam” is both a name and the ordinary word for “human,” and the passage itself shifts between singular (“him”) and plural (“them”), which invites more than one way of describing the referent. “In the day” is also used idiomatically in biblical Hebrew, but it can also be read more literally.
What this passage clearly contributes
Explicitly, it establishes five points: (1) a new, formal family record is beginning; (2) human origin is grounded in God’s creative act; (3) humanity is made in God’s likeness; (4) humanity exists as male and female and is blessed by God; (5) “Adam” is presented as a shared name tied to that creation moment. Theologically, these claims set a tone for the genealogy: the line of descendants is traced within a creation framework of dignity (likeness), relational humanity (male/female), and divine favor (blessing), even as the narrative moves forward through generations.