Main point: Humility before God.
God has made it known to David that he will not build the temple, but his son will and that He will establish his line forever. David comes before God humbled saying who am I? He declares God’s greatness along with declaring his own short comings.
I need to remember this. Who am I that God has already blessed me so much, that He would have plans for me, that He would love me, use me, take care of me, thrill me. Who am I? I don’t deserve to be able to do anything for God. He has counted me as righteous as His Son and I don’t deserve that. God is good.
This shows the gospel in showing the shortcomings of man yet the imputation of God to count men as worthy and righteous because of Jesus.