By designating Jesus as the firstborn Paul indicates that he is the fulfillment of the commission originally given to Adam. This view is strengthened when we see that the words eikon and prototokos are parallel in Colossians 1:15. Israel was appointed to reclaim what Adam had lost, and the Davidic king played a representative role in this reclamation project. What Paul suggests here is that Jesus Christ is the fulfillment of what both Israel and David were called to be. In other words, Jesus Christ is the true israel and the true Davidic king precisely because he is God’s sovereign ruler over the world. He fulfills the task of ruling over the world in God’s name as Lord and Christ. His lordship over the world is scarcely surprising since he is the agent of creation (Col 1:16) and also the one who continually sustains the created order (Col 1:17). The one who rules over the created world is also the one through whom the creation came into being.
Quoted from Schreiner, T. R. (2001). Paul, Apostle of God’s glory in Christ: A Pauline theology . Downers Grove, Ill: InterVarsity Press, p. 176.