What does Genesis 5:11 mean?

The fact that man is destined for physical death is, at this point in human history, the most visible impact of the fall. Over and over, this passage will repeat the fate common to all men: "he died." Whether at the end of centuries, decades, naturally or by some mysterious cause (Genesis 5:24), all men are destined to leave this life and come face-to-face with God.

Enosh died at 905 years old, compared to his father Seth at 912 years old and his grandfather Adam at 930 years old. As stated repeatedly in this chapter, these are not the only sons (or daughters) of these men. That, combined with long lives, means that children of this time had access to an extremely long line of ancestors. By the time we arrive at verse 32, we will see that Noah's father, Lamech, was born before Adam died. This means Noah, and his son Shem, had the opportunity to speak with someone who was just one step removed from a direct eye-witness to the origins of mankind!