You're all over the place. I'm very familiar with the Bible. I was a full time minister for 2 years. He can promise to deliver the Israelites and that does not erase the event that you believe in where he murdered the world. I suppose I can conclude you are having trouble reconciling this because you can't stick to the event in question.
1. Ok.
2. Wrong conclusion.
Here's the Biblical description (the meaning of which you and I are very familiar)--
7So the LORD said, “I will blot out man, whom I have created, from the face of the earth—every man and beast and crawling creature and bird of the air—for I am grieved that I have made them.”
8Noah, however, found favor in the eyes of the LORD.
As for mercy:
16And whenever the rainbow appears in the clouds, I will see it and remember the everlasting covenant between God and every living creature of every kind that is on the earth.”