Again, you may believe in the literal translation of the Bible or the allegorical translation. Indeed, much of what happened before Abraham is probably just that, allegorical and nothing more.He is right LRS.
The global flood myth is primarily invoked to defend young Earth creationism.
The water vapor in our atmosphere is directly related to temperature of the atmosphere. The hotter it is...the more water vapor it will support.
There is a staggering 37.5 million billion gallons of water in the Earth's atmosphere at any given time.
As huge as that number sounds...if all the water vapor the Earth possesses condensed simultaneously it would cover the Earth with 2.5cm of rain. Or 1 inch if you aren't feeling metric. That includes land and sea.
It may ruin a picnic, but flood the Earth...hardly.
It is just impossible.
It is like telling a three year old how his mother got pregnant! How do you explain things to people who are illiterate sheep herders?