A simple examination of the text. The pronouns regard God in the first instance, and His Son in the last three.
God gave Jesus a place of preeminence in the world. This is best demonstrated in the church, which is figuratively described as His body. As the head is to the body, so is Christ to the church. He is the authority, He is the guide, He is the director.
As the church (His body) does His will on earth, it accomplishes everything God intends. This is our purpose as we live here — do Christ’s will, and accomplish His purpose.
Another truth in the metaphor of the head and the body is that there is one of each. One head and multiple bodies is a monster. There is only one body, on church (cf. Ephesians 4:4).
One body with multiple heads is a monstrosity as well. For any to exalt themselves by taking authority that belongs to Christ is wrong. He has “all authority in heaven and on earth” (Matthew 28:18).
Christ fulfills us completely. His power, goodness, might, love & preeminence empower us in all things (1 Corinthians 15:58).
