When we come to this passage, the seed of sin that was introduced in the Garden of Eden and has generated in the hearts of mankind and its consequences now come to fruition.
Here we see the Corruption of the Race of Man in that his wickedness is great due to the Condition of the Heart. This causes great Concern for God, so much so that He was sorry that He had created Man and that man's sin grieved Him. I believe that it was not the creation of man, but the condition to which sin had taken to man that brought this grief. The extent of this Condition resulted in the Condemnation of man's sin and the destruction of Mankind via the Flood.
We note, then, that God's judgment on Man was due to the corruption of his behavior which stemmed from his heart, (a term used to describe that place in man where the will/conscience resides). Man's wickedness (moral evil) was great (in abundance) and every intent of the "thoughts (contrived plans) of his heart was only evil continually". What was on the INSIDE was revealed on the OUTSIDE.
Prov 27:19 reminds us that "As in water face answereth to face, so the heart of man to man." KJV
Ps 36:1-4 records "The transgression of the wicked saith within my heart, that there is no fear of God before his eyes. 2 For he flattereth himself in his own eyes, until his iniquity be found to be hateful. 3 The words of his mouth are iniquity and deceit: he hath left off to be wise, and to do good. 4 He deviseth mischief upon his bed; he setteth himself in a way that is not good; he abhorreth not evil." KJV
The actions of moral evil are reflections of the heart that has rejected God.
Romans 1:21 reads "Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened". KJV See also Romans 1:28ff and ask whether the describe events occur in our society and whether such could have a connection with our ejection of God.
We reap what we sow...
Mr. Harry D. Clarke gave us the simple chorus that may serve as a remedy to our nation's malady of heart disease.
Into my heart, into my heart,
Come into my heart, Lord Jesus;
Come in today, come in to stay;
Come into my heart, Lord Jesus.