Nonsense of Noah
6:5 And God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.
But God rewarded Cain by threatening anyone who killed Cain with a sevenfold
4:15 And the LORD said unto him, Therefore whosoever slayeth Cain, vengeance shall be taken on him sevenfold.And the LORD set a mark upon Cain, lest any finding him should kill him.
So if killing another results in protection by God and BTW finding a nice wife, raising a child and founding the city Nod, what greater wickedness lurked in the hearts of the 30,000 or so people who inhabited the earth at that time? Some 9 generations removed from Adam and Eve?
How did they get so bad so fast? Apparently murder isn't enough to make you bad.