The Great Flood story, in terms of time, gives much more detail than other Genesis stories. It gives detail to the month and even to the day.
One reason I see comes from a counting perspective.
Genesis 8:13-14 less Genesis 7:11 shows the Great Flood lasted exactly 1 year and 10 days. However, there are 2 or more other ways to tell that the Flood definitely lasted more than one year. That is by using the 150's with the 7 days, etc.
The following takes that to a something else I see as very important. See below if you choose.
[Parenthood and childhood can't possibly begin at birth when "age", "years old" and "lifetime" begin. Fatherhood (& thus motherhood) and childhood, per the words combined with the age numbers in Genesis, can only begin at conception.
Otherwise, these 3 verses below, together, are impossible and haven’t been explained, as far as I know.
Gn 5, 32: When Noah was 500 years old, he became the father of Shem…
(Noah was 500 years old when Shem was conceived, but Shem wouldn't be born for about 9 more months.
By the time Shem was born, Noah would probably have been 501 years old.
Noah would then have been about 501 years older than Shem).
Gn 7, 11: In the 600th year of Noah’s life…the floodgates of the sky were opened.
In the 600th year of Noah's life, his age was only 599. (Again, his life began at his conception too.)
(Based on the two verses above, Shem would have been only 98 years old when the floodgates were opened; that is Noah's age of 599 when the flood began less: the 501 years older in age than Noah was of Shem).
Gn 11, 10: When Shem was 100 years old, he became the father of Arpachshad, 2 years after the flood.
(Since Shem was 98 years old when the flood began, 2 years later he would indeed have been 100 years old).
That is the only way these 3 verses from 3 different chapters fit and can be true together.
Note: We cannot remove "2 years after the flood" and simply claim that to be a mistake. If we were to remove it, then Noah's grandson Arpachshad, would have to have been born on the ark. That's because Shem would have been 100 while on the ark, thus becoming the father of Arpachshad while on the ark. No grandchildren such as Arpachshad got off the ark, only Noah, his wife, his sons and his sons' wives. Then God told only Noah and he three sons to be fertile. They were the only men who got off the ark and became fathers later].