"This chapter serves at least three ends in the scheme of Genesis. First, it bears witness to man's value to God, by naming individuals and stages in this early human phase: each is known and remembered. Secondly, it shows how the line of Seth the 'appointed' (4:25) led on to Noah the deliverer. Thirdly, it both demonstrates the reign of death, by its insistent refrain (5b, 8b, etc.), and conspicuously breaks the rhythm to tell of Enoch, the standing pledge of death's defeat."
Derek Kidner, Genesis, Vol. 1 of Tyndale Old Testament Commentaries, ed. D. J. Wiseman, (Downers Grove IL, Intervarsity Press, 1967), 79-80.