Genesis 5:9-11 ESV
When Enosh had lived 90 years, he fathered Kenan. Enosh lived after he fathered Kenan 815 years and had other sons and daughters. Thus all the days of Enosh were 905 years, and he died.
Seth's son was Enosh(or Enos in KJV) and his name means "man". The word denotes mortality and the frailty of the human condition. Eve conceived man that would be less than the man Mary would later conceive through the Holy Spirit. That man was mortal and frail, but more and completely alive. He was the only man that could die for us because He was the only man truly alive. The rest of us were dead in sin.