Day: a unit of measurement typically referred to as a rotation of the Earth on its axis.  However among Christians this "day" can be any length of time.  It can be 5 rotations of the Earth or 700 rotations of the Earth as long as it helps them explain something Biblical.

I think the distinction some bible literalists make between man who lives one-hundred and twenty years, and man who lives nine-hundred years, is if they existed before the Fall, or Deluge.  If we are to believe the likes of Kent Hovind or Dr. Carl Baugh, prediluvian man enjoyed an atmosphere much richer in O2 than ours, promoting vastly superior intelligence and gigantic proportions.  I will have to scour the internet a little to find this, but Dr. Carl Baugh was once convinced that he should insert himself into a chamber fllled with O3 (ozone), since O3 is somehow "better" than O2.  He thought he would become a hyperintelligent giant.  Luckily for him, one of his friends who was a chemist talked him out of it before he was killed.

I think abraham lived to be 175 years old. Yet we learn from history and science that primitive man lived to his 30's. And it is only the most recent generations live to their 70s or 80s. Yet there are a number of well known people who lived that long hundreds of years ago, like my favorite composer Papa Haydn, and Bach lived a long life. Maybe Ben Franklin. Moses was 80 when he stood before Pharoah and died well over 100. Yet the bible doesn't indicate that was remarkable. The Pharaohs didn't live to such great ages. Lots of ancient religions talk about people living to unbelievable ages. I am confused on this matter and science hasn't cleared it up for me either.

Actually, I understand that the figure of average life expectancy back then was low, but that was due to much higher infant and child mortality.

The maximum age that people could live to wasn't that much less than today, so you could still reach your 80's or more, once you survived through your earlier years.

As far as Biblical time periods go, I don't really know. I know that medieval queen Eleanor of Aquitaine lived to be in her eighties, whether that was unusual for the time period of the Middle Ages or not, I am not certain.

Most of the books around this time period are focused on members of royalty due to the fact that so little is known about the peasantry of the medieval world.

There is one book called "Daily Life in the Middle Ages" that touches upon it quite well. The worst by far, that I have ever read was called "A world lit only by fire,". which was filled with so many historical innacuracies and outright unproveable tales that it deserved to be pulled off of the shelf.

Most of what I have read claims a 50% death rate for women of childbearing years.  90% for the first year of infancy in the middle ages.  My numbers may be way out of date, it has been awhile since I paid any attention.

Oh, and there is no evidence Moses ever existed.  No mention of a Canaanite (they were all Canaanites then) close to Pharaoh, let alone one raised as a foster brother.  No mention of a mass exodus of Canaanites, nor that they were all enslaved.  On the contrary, many were farmers, merchants and a few managed to rise up to the civil service.  No mention or indication of plagues, including no economic downturns.  See:  The Bible Unearthed.  Available at your local library.