You're mushing the story. Nowhere in the Noah narrative is it said that "God created evil." In fact, nowhere in that narrative does it say that "God created humanity, knowing in advance that it wouldn't live up to [God's] expectations." Your argument is a straw man.
You're looking at this from a standpoint of "God doing something to a bunch of individuals," rather than from the standpoint of "the collective plight of humanity."
You can't mush the message and come up with a good analysis. Rather, your analysis takes into consideration things that are beyond the narrative in question.
It's not a straw man.
Isaiah 45:7 in the King James Version reads, I form the light, and create darkness: I make peace, and create evil
Clearly the bible states that god creates all things, including evil. Also, the god of the bible is portrayed as omniscient, meaning he knows all including the future. I'm not using a strawman, I'm using the mainstream doctrine of christianity. So, If god creates all, good and evil, and god is omniscient, then clearly god knew in advance that his creation would not live up to his expectation, but created them anyways. And he also created the evil that they apparently partook of. So, where was the strawman?