"Firstborn of every creature" does not mean that Christ was "born first" in the sense of being the first created being. Rather it refers to Christ's position of supremacy over all of creation by virtue of the fact that He is the Creator of all things (verse 16).

Notice the word "For" at the beginning of verse 16. This word introduces a reason or explanation for what Paul had just said in verse 15. Why is Christ the firstborn of every creature? It is because He created all things (verse 16). 

The word "firstborn" in Colossians 1:15 refers to positional priority not temporal priority. See Exodus 4:22 where Israel is called God's "firstborn." Israel was not the first nation that God brought into existence, but positionally as God's chosen and privileged nation Israel was supreme. In Psalm 89:27 King David is placed as firstborn, but David was actually the last-born son of Jesse! The term obviously was not used to denote chronological order. Thus the term is used in Colossians 1:15 to express Christ's priority to and preeminence over creation. He outranks every created thing because He is the Creator!

There is a Greek word which means first created (protoktistos) but Paul did not use this word of Christ.

The Jehovah's Witness translators of the Bible (New World Translation) have added the word "other" four times in Colossians 1:16-17 even though it is not in the Greek text. Their view is that Jehovah created Christ and that Christ then created all other creatures! However this contradicts John 1:3 which says that everything that was made was made by Christ.  If Christ was made (as the Jehovah's Witnesses wrongly teach), then John 1:3 would imply that Christ made Himself (which the Jehovah's Witnesses do not teach). Instead, John 1:3 teaches that Christ is the uncreated Creator!

Colossians 1:17 teaches that Christ is before all things. If Jehovah created Christ, as Jehovah Witnesses teach, then we could say that Jehovah is before all things. (Jehovah existed even before Christ was created, according to Jehovah's Witness doctrine.)  But it would not be true that Christ is before all things. This is why the Jehovah's Witnesses must insert the word "other."  [Christ is before all (other) things.]  Remove the word "other" (which is not found in the Greek text and should be removed) and the verse contradicts Jehovah Witness doctrine. Those who believe that Jesus Christ is the eternal Creator-God have no problem with these verses exactly as they are in the Greek text.  There is no need to insert the word "other."

God gives serious warning to those who wrongly add to His Word (Rev. 22:18).

For additional study on this passage:  See Colossians 1:15