God considers many things before he undertakes an action.
There are so many spiritual applications we can make with the entire narrative of Genesis 6-8.
1) The fact that rebel angels can have a negative impact on the way humans behave. The earth had become "filled with violence" on account of the activities of a race of supernaturally produced bullies, whose dominance and immoral ways had permeated every human activity. It became a natural way of life for them. It was not natural for Noah.
2) That God will not tolerate interference with his purpose and will step in directly only when necessary to keep this plans on track, otherwise he has given the devil a free hand to test the human race. (see Job Ch 1 & 2)
He will not allow us to go beyond our individual level of tolerance however. (1 Corinthians 10:13) The devil wants to test our resolve to serve our God in love. He claims that we only do it out of self interest.....that if he makes the going tough, we will cave in and abandon our Creator.....we can prove otherwise.
3) That God can determine who is worthy to live and who is deserving of death by the choices they make. That is his right to determine as our Sovereign ruler. But he judges the heart and the motives, not just the actions.
Noah is called "a preacher of righteousness" to those who were victims of the flood. He gave them options to live and they ignored his warning. Jesus used this prophetically as an example of the greater judgment to come. (Matthew 24:37-39)
4) God can give humans instructions on how to save themselves, rather than have them expect that he will just shield them from the devil's activities with no effort on their part. Jesus told Simon Peter...
"Satan has demanded to have all of you to sift you as wheat. 32 But I have made supplication for you that your faith may not give out".
The devil is testing all of us....and the majority are failing, just they did in Noah's day....and for all the same reasons.
It seems we never learn.
Humans must follow God's directions to the letter if they want to survive the final judgment. We have choices to make and an example from the past to use in our decisions. For those who obey the Creator, and prove that the devil is a liar, the rewards will be in keeping with what they have endured, as it was with Job. (Job 42:12-16)
That is how I see things.