It's the power of the pen - so to say.
According to the Bible it was not a global flood until 1611 when the KJ Bible translated - mistranslated the Hebrew text. -- The original story said it was a regional flood.
Btw: There was no Hebrew word for Planet Earth in those days. The authors did not even know about Mt Everest or that there was a land far far away. So how could the original Bible text say the flood was global?
Please excuse this copy and paste job:
The original Bible text (scrolls) never said it was a global flood.
The History channel covered that in one of their documentaries.
. Noah's (small) world was flooded; not the whole world as we know it today. (The documentary indicated it could have occurred in Mesopotamia.)
Gen. 7:4 - For yet seven days, and I will cause it to rain upon the earth [erets] forty days and forty nights; and every living substance that I have made will I destroy from off face of the earth [adamah].
The part "face of the earth" in this verse in Hebrew reads as ;paniym adamah. These two words don't mean the *whole earth". but a territory or country. Ergo: the Bilbe doesn't say it was a global flood.
Incidentally, when I was in the jungles of Vietnam, it rained for a little more than 40 days and nights during the wet-monsoons. -- It was a yearly event. It did not flood the whole world. -- The people of that area build their houses on stilts just to prepare them for those wet monsoons that usually lasted about 40 days. - go figure.
Secondly, - the animals to be saved were the local animals -- they did not mention Elephants and Giraffes, like the Sunday school pictorials. --- penguins and aardvarks were not mentioned in the Bible either.
Thirdly, the Ark was an expression for "container/containers that floated"
fourthly, Those containers (arks) were already built. They were called barges which were used for commerce during that time - for moving grains and livestock down river. Also wine as I recall.
fifthly , Those containers simply needed to be amassed and tied together, by Noah or whoever.
Some one must have asked "How did Noah escape the flood?" And someone else said, "write that he had a big boat." "How big should a say the boat was?" "Egad!! Say it was lots and lots of cubits." ....... "What's a cubit?"