כִּי טוֹב "It was good" is mentioned only when what was created is complete. (Rashi, Ramban). Only by an Adam it doesn't say: כִּי טוֹב "It was good", because an Adam is always Chasser (incomplete) since he needs to always grow. Although not getting a כִּי טוֹב "It was good", sounds like a Chisaron, this is the exact greatness of a human, i.e., when he feels he's not good enough and has to grow. Adam gave 70 of his original 1,000 years of life to Dovid.
When Adam sinned, he said: הָאִשָּׁה אֲשֶׁר נָתַתָּה עִמָּדִי "I sinned because of the woman You gave me", i.e., it's not his fault. But when Dovid sinned, he was Modeh (admitted) and he said: וְחַטָּאתִי נֶגְדִּי תָמִיד my sin is before me always. He was always in a mode of constant need for improvement. The word "Chet" actually means to be "missing", like it says about the archers of Shevet Binyamin who were such expert sharp-shooters that: וְלֹא יַחֲטִא they never "missed" their mark. The true Adam is the M'vakesh (seeker) who is always trying to improve.