Keeping in mind that the first principles of bible interpretation are grammar and immediate context, I see nothing in the grammar or immediate context of Genesis 6:6-7 to indicate that God’s regret over his own decision to create man, was intended by the author any less literally than Genesis 1:1 was intended.
For that reason, you have the uneviable task of reconciling your “god is perfect” belief, with God’s own admission that the way mankind turn out, caused God to be sorry he ever created man:
6 It repented him that he had made man on the earth. And being touched inwardly with sorrow of heart,
7 He said: I will destroy man, whom I have created, from the face of the earth, from man even to beasts, from the creeping thing even to the fowls of the air, for it repenteth me that I have made them. (Gen. 6:6-7 DRA)
Now what should we do with an interpretation of a bible verse which lacks any support from the immediate context?
And in the immediate context, v. 5 refers to something you think is literal (God was aware that men became wicked), in v. 8 Noah really did find grace in the eyes of the Lord.
So the immediate context not only doesn’t support the “anthropomorphism” interpretation, but indicates v. 6-7 were intended as straight forward historical reporting.
In other words, the position of open-theists (who believe God can and does change his mind, or make mistakes, or regret having done something) is quite defensible from the bible.
In that case, God could easily be biased while still being god. Why? Because God is defined by his own self-declarations and actions. If that weren’t the case, we could never “check” the accuracy of any theological statements. The church being criticized could just say “but we never get anything wrong”, and that would be wonderfully comforting way to feel better about turning away from criticism, but it would amount to the type of cultic thinking responsible for making Mormons so difficult to evangelize. When you criticise their leaders, you violate rule #1, there is no such thing as Mormon error.
Have you ever attended a church who believed their own infallibility was beyond criticism? There ain’t no talking them at all, right?