Question: Any thoughts to why they lived so long then 900+ years and we now only 70+ years? Answer: After the flood we see a dramatic change in how long people lived. It makes sense to me that this is because there was a protective water canopy around the earth (Gen 1:6) which shielded the earth from harmful rays that are part of the breaking down of cells and aging process today. That water canopy was poured out on the earth in the flood so it no longer protects the earth. That is one view, it is not clearly taught in Scripture but it makes sense to me. -PJ
A canopy of water around the earth allowed people to live much longer than today.