I can't speculate over that assumption.
I can only go by what the book actually says.
Notice the lineage of the hunmans that survived the Flood...
And that was after the Fall which resulted in a physical change to Adam & Eve causing them to be different from the way they were created. So, when Seth was born, Adam 7 Eve may have retained similarities with God’s image but they were no longer in his image.
I can't speculate over that assumption.
I can only go by what the book actually says.
Notice the lineage of the hunmans that survived the Flood...