"After the flood" is a speculation based on conjectures not in evidence.
"Imagine" is a nifty choice of words. We can imagine all manner of things. I have a good imagination. I imagine that the skygod Zeus got really pissed off and decided to kill all the people he created, just to show them who was boss.
He could have done this by {poof}, but instead He decided on {poof} a flood. Good ole Zeus--he was very particular to teach a moral lesson. He liked Noah for some odd reason. But Zeus, who used to have a soft spot in his heart for babies, killed them all. Zeus was prevailed upon by sinners--mostly mothers--and Zeus, being Zeus, could have spared all the innocent babies. He might even have opposed abortion. But Zeus, being Zeus, killed them all. Killed their souls. Drowned everybody except ole Noah.
There is a great moral teaching in this story.
"Don't piss off Zeus?"