I suppose that humility is not listed in the fruit of the Spirit in Gal. 5 because it is part of our freewill; we can choose to be humble.
James explains that humility is key to intimacy with God, and we see this modeled throughout the Scriptures (e.g., Moses, David, Jesus), as well as repeated in Proverbs.
James 4:6, 10 NIV
But he gives us more grace. That is why Scripture says: "God opposes the proud but shows favor to the humble."
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Humble yourselves before the Lord, and he will lift you up.
John the Baptizer considered himself unworthy to perform even the basic service of a slave, washing Jesus's feet.
John 1:27 NIV
He is the one who comes after me, the straps of whose sandals I am not worthy to untie."James reminds us that our knowledge is so limited compared to the Father's omniscience, and our time in this life is so brief compared to eternity.
James 4:14 NIV
Why, you do not even know what will happen tomorrow. What is your life? You are a mist that appears for a little while and then vanishes.
Father, I want to be humble. Holy Spirit, please help me choose to be humble. I want my heart to be fertile 100-fold soil. Please grow your life deeper in me. Lord Jesus, I want to honor your reign. I love you.