Back to the basics.
Man is mortal. Every men are sinners. Through one man sin has entered into the world. So basically we are sinners. While still sin in this world, how can he lift himself. Because redemption is through is death only. Jesus came into the world with human body. So he has to obey that rule. Even he don't know sin, as long as he is human body he obeyed to human rules. So he don't want to lift himself by saying, "yes I am". It's called humbleness.
Note this after his resurrection Paul had noted like this " i Don't know Jesus in flesh anymore".
Those who has ears, let them hear.
God bless you.