It is true there was a natural deluge of massive proportions in our planet's recent history. We have the ice age coming to an end about 12,000 years ago. It is reported that ocean levels raised about 400ft worldwide. It is estimated that what used to be among the world's best arable land about the size of Europe and China combined, is now under water. The vast majority of the world's population was wiped out. It was a massive catastrophe. But, it was not anything of the order that is reported to have happened in Noah's day. However, I'm sure there were many who wouldn't have known the difference and if those souls are still among us they certainly carry with them buried in their consciousness a recollection of their experience.
If there was a flood based on H2O I am in favor of drawing on the distinction of earth vs. planet. It could have been a localized flood. There is evidence in Arizona at well over 5,000 ft elevation of vast amounts of water carried debris that is now fossilized. There had to have been a massive tsunami that went to great heights with great force and volume to have carried that material and deposit it where it did.
However, as I read the bible I have come to see a metaphoric key that acts as a decoder for what is written in the pre-Abrahamic timeframe. When the people and "creatures" were spoken of it is said "wherein dwells the breath of life". This looks innocent enough on the surface but there are linking keys that lets you know a different kind of life than we normally think of is what is being referred to.
This "life" could be thought of as a certain level of knowledge or spiritual enlightenment that distinguishes a person who is a living soul in God's eyes and who is just a zombie in God's eyes.
Take notice of Adam. He was created from the dust of the ground and then God put into him his "breath of life". That act turned Adam into a living soul. (Gen 2:7) If we want to know more precisely how this happened to Adam, we can look at what Jesus did to his disciples in John 20:22. Jesus breathed upon them and commanded them "receive ye the Holy Ghost". At that time his disciples were brought from a state of spiritual death to a state of spiritual life. They were brought back into the presense of God because the Holy Ghost is a member of the Godhead and now it dwelt in them. Their separation from God was healed. Death is separation and resurrection is reunion.
Thus, as far as I'm concerned, the most important resurrection Jesus brought and instituted is the bestowal of the Gift of the Holy Ghost, which was a new ordinance the Jews did not have because they rejected the higher laws under the Melchizedek Priesthood level of things. As a people, they were under the Aaronic level that dealt only with the carnal commandments. They were not functioning on the higher level of the laws. Thus, Jesus came to raise them up to spiritual life, the kind of life Adam had, but they rejected it. Thus, they remain spiritually dead to this day. But, I digress.
Thus, Adam being the first "living soul" does not necessarily require him to be the first man alive on the planet as we would normally think. This planet could be full of people who are physically alive and well but all spiritually dead as a doornail. If God selects a man, a fleck of dust, and puts into him the "breath of life", which is the "Holy Ghost", then that man who was physically living now also becomes spiritually living.
So, I posit, the flood that took place in the days of Noah was a kind of flood that drowned out the "breath of life" from all those upon the earth. Thus, it didn't kill their physical bodies at all. It simply drove out of them their level of enlightment due to having the Holy Ghost driven out of them. They were flooded out by the philosophies of men and reduced themselves to zombies in God's eyes.
Now, as for the ark and all the animals. The ark floated up above the flood of man's garbage thinking. It was an ideological boat that kept them from drowning. Also, the animals coming in two by two wasn't actually animals in the literal sense. These were animals as can be understood from the metaphor of the creation account. They were all representative of various classes of people at different stages of enlightenment. Christians are at the "fish" level in the evolutionary rung of things so all of these individuals who avoided the flood were a cut above this class of people. They were the caliber of people such as the founding fathers of the USA, who had a realatively high degree of enlightenment but they were not the full stature of Adam or Noah himself. It became the duty of these individuals to attempt to seed enlightenment back into the civilizations of the world that had all become zombies as far as God was concerned.