Genesis 5

This covers the genealogical line between Adam and Noah.  This line goes through Seth, in contrast to Cain.

As a literary device, the genealogical information links the two major stories and time frames.  Verses 1-2 even reiterate the creation of mankind, male and female, by God.  The genealogical data then takes us from the time frame of the creation of mankind through the centuries to Noah.

A few other things stand out to me.

* Adam and Eve had other sons and daughters.  (verses 4-5).  However, it is still unclear when and how many of each they had.  The textual emphasis on Seth suggests they had the other children after Seth.  Nevertheless, the statement is one possible to how Cain and Seth had wives.

Another major problem for me about Cain and Seth marrying their sisters (daughters from Adam and Eve) is the ban on incestuous relationships we find in the Mosaic Code.

* Based on the ages and timespans, Adam and Eve would have seen many generations of their descendants.

* Many people's lifespans come close, but do not exceed, a millennium.  It is like an unobtainable goal.  I would not read too much into it, but it is an interesting corollary to the use of a "millennium" in the Book of Revelation.

* Noah is named as a consoler for the curse on the ground. This is an interesting statement.  One theory I read is that this refers to Noah development of wine-making.  Later in Genesis 9:20-21, it states that Noah was a man of the soil and the first to plant a vineyard.

* Both the Seth line and the Cain line include a man named Lameck.  In the Cain line, he was a murderer, who followed in Cain's footsteps.  In the Seth line, he is the father of Noah.  Thus, we have two contrasting lines of the descendants of Adam and Eve.  One contains murderers and one contains people faithful to God.