If one reads The Epic of Gilgamesh you will find not only the Flood story, almost verbatim, you will also find a section almost identical to Ecclesiastes. These were very popular stories of this time and the chroniclers of the OT used this popular work in the Bible as a foundation to engage the people and then relate a story of spiritual significance. The Flood of Noah is not literal. To see it as literal is to completely miss the point of this teaching.
The Flood is a Flood of Revelation received by Noah. Rain of 40 days and nights means that Noah received a Revelation from God for 40 years. The Ark is the Ark of a Covenant Noah made with God that those who entered into this Ark, the Teachings of Noah from God, were protected from the ravages of self and passion, the material world, that will destroy you spiritually, just like a real flood destroys the body.
The earth and humanity would never have recovered in such a short time from a flood of such proportions as imagined with the Flood of Noah. It is a spiritual story demonstrating that those who enter a Covenant with God and live by His precepts are protected, it is as if they entered a great boat that could protect them even if the entire planet was flooded.
As a literal story the Flood of Noah makes no sense, is contrary to science and common sense and is utterly impossible to then further imagine that humanity today is the result of the inbreeding of 8 Middle Eastern people who then gave rise to Aboriginals, Pygmies, Scandinavians, Zulu, Chinese, Polynesians, etc, etc.
There would have been a need to hold nearly 4,000,000 animals many of which would have been predatory animals. The food requirements for these animals would have filled many Arks alone. The moment upon release that a predatory animal ate another animal that animal line then became extinct. Kangaroos and platypus released in Turkey are unlikely to have walked back to the Australian land mass.
The Flood of Noah is an important spiritual story and when taught as a literal story it loses all meaning and inoculate people against religion.