Jesus was not created. As John says:
"He was in the beginning with God. All things were made through Him, and without Him was not any thing made that was made." (John 1:2)
Paul's context in Colossians 1:15 is that Jesus is preeminent over all creation, just as David ~ what was the youngest son of Jesse and thus of all his brothers ~ was made King and therefore firstborn over physical Israel. As we read in Psalm 89:
"I have found David, my servant; with my holy oil I have anointed him, so that my hand shall be established with him; my arm also shall strengthen him. The enemy shall not outwit him; the wicked shall not humble him. I will crush his foes before him and strike down those who hate him. My faithfulness and my steadfast love shall be with him, and in my name shall his horn be exalted. I will set his hand on the sea and his right hand on the rivers. He shall cry to me, ‘You are my Father, my God, and the Rock of my salvation.’ And I will make him the firstborn, the highest of the kings of the earth." (Psalm 89:20-27)
The context is exactly the same in the New Testament of Jesus ~ the Greater David ~ but on a far greater level (as David himself acknowledges in Psalm 110, calling Jesus his Lord ~ here:
"For those whom He foreknew He also predestined to be conformed to the image of His Son, in order that He might be the firstborn among many brothers." (Romans 8:29)
"He is the image of the invisible God, the firstborn of all creation." (Colossians 1:15)
"And He is the Head of the body, the church. He is the beginning, the firstborn from the dead, that in everything He might be preeminent." (Colossians 1:18)
"And again, when He brings the firstborn into the world, He says, “Let all God's angels worship Him.” (Hebrews 1:6)
"...and from Jesus Christ the faithful witness, the firstborn of the dead, and the ruler of kings on earth. To Him who loves us and has freed us from our sins by His blood..." (Revelation 1:5)
And the amazing things is that we will all be made firstborn ~ co-heirs with Christ ~ in that same sense when Jesus returns, the Judgment is concluded, the new Creation is consummated:
"...and to the assembly of the firstborn who are enrolled in heaven, and to God, the judge of all, and to the spirits of the righteous made perfect..." (Hebrews 12:23)
And we can live as though that's true now, because it is an absolute certainty... it's not yet made complete, but as if it's already happened. Glory be to our great God.
Pssst. This is coming from one of those "pessimistic" Calvinists...
:)
Grace and peace to you.