Imagine, Adam reached the age of 930. He experienced nine generations born after him, but did not live to see Noah. Noah was number ten, born in the year 1056 after Adam. Noah was the first to only have heard of Adam. Because Adam had been gone for 126 years when Noah was born. Noah himself lived for 950 years. The flood came when he was 600. That was in the year 1656 after Adam. In that year, only one of the fathers before Noah was alive. That was Metusalem, Noahs grandfather, who died that year. He reached the highest age of all, namely 969.
By Noah, God decided that the days of man should be 120 years. Noah, though, lived until the times of the Babylonian confusion, and I believe he must have missed the confusion by only a few years. Abraham, we know, left Babylonia in the times of the confusion. He must have known or at least seen Noah. Because Abraham was 60 years old when Noah died. Abraham left Mesopotamia 75 years old. Abraham lived for 120 years. So the years of living decreased throughout the years, and in the times of Moses, about 12-1300 years before Christ (and that I believe must have been in the 27th or 28th generation after Adam) the average duration of life was 70 years, 80 at the most, according to Psalm 90, which one believes is written by Moses. Moses himself challenged this fact, though: He was 90 when he spoke to Farao and 120 when he died.