“He existed before all things, and all things are held together in him.” (Colossians 1:17, CEB)

Paul corrects the the wrong ideas that had been taught. Christ is not some part-angelic being, but God himself. God is invisible, yet people can see him and know him in Jesus Christ. Jesus is God and therefore was not created. He existed before creation, and is superior to all created things. In fact, he himself is the Creator. He is the source and controller of all things, seen and unseen, including the world of angelic beings that false teachers liked to talk about. More than that, he is the goal of all creation’ all things exist for his glory.
Christ, through his infinite power upholds the universe and through his wisdom preserves the cosmic harmony. None could do this but one who is divine; and hence we see the reason why he is represented as the image of the invisible God.
Sources:
Bible Gateway
MySword for Android. Riversoft Ministry, 2011-2019.