What does Genesis 6:6 mean?

The Bible rarely speaks of God experiencing "regret." The Hebrew word used here is yin'nā'hem, from the root word nacham. The word is exclusively about emotions: a feeling of pain, sadness, or unhappiness. The word does not imply that God feels He has made a mistake, or that He wishes to have done differently. It is possible to experience grief and "regret," as used here, without implying an error. Any parent who has held a crying, upset child as they receive a shot has experienced exactly that. Such a parent is "grieved" over the pain, but has no illusions that this was the wrong decision.

However, this verse does mean God is unhappy with the current state of man. This is a low point in the history of humanity. God is troubled. He is "grieved," or "pained," by the outcome of His act of creation. The men and women, however, do not grieve their own sin. They do not repent. God's grief stands in great contrast to that of His creatures, who blindly continue to indulge in every sinful thought, action, and word that begins in their hearts and minds.

Left alone, the evil of man will eventually overtake the entire race, and there will be no godly people left. There will be no line to produce the already-promised Messiah (Genesis 3:15). God will not let the earth go on like this indefinitely.