Folah, please read my posts. The term does not relate to the life span of a person, but when they father a child.

Thus Adam's "generation" was 130 years.

And one more time: in the 1st century CE a generation was around 20-30 years (fatherhood).

Since the main point here is that Jsus said that generation WOULD NOT DIE and they are all dead it proves that focusing on Genesis 5 is a red herring and nothing more.
And everything that Sarah tells you, listen to her voice. Genesis, 21:12