The biblical use of the word “firstborn” can have different meanings. The first born child in a physical family is one of its meanings. This is exemplified in Luke 2:7:
“And she gave birth to her son, the firstborn, and she bound him with cloth bands and laid him in a manger, because there was no place for them in the lodging room.”
Another meaning of the word “firstborn” is pre-eminence (This in turn means to have paramount rank, dignity, or importance). For example, notice what Psalm 89:20, 27 states:
“I have found David my servant; With my holy oil I have anointed him...Also, I myself shall place him as firstborn, The most high of the kings of the earth.”
Furthermore, “firstborn” in the scriptures can also be a title which is transferable. This is indicated by the information from two set of scriptures. The first is Genesis 41:51-52, there it states:
"So Joseph called the name of the firstborn Ma•nas´seh, because, to quote him, “God has made me forget all my trouble and all the house of my father.” And the name of the second he called E´phra•im, because, to quote him, “God has made me fruitful in the land of my wretchedness.”"
In the above scripture Manasseh is the firstborn. The second is Ephraim. The firstborn title is transferred though to Ephraim as indicated in Jeremiah 31:9:
"With weeping they will come, and with [their] entreaties for favor I shall bring them. I shall make them walk to torrent valleys of water, in a right way in which they will not be caused to stumble. For I have become to Israel a Father; and as for E´phra•im, he is my firstborn."
With all of the above in mind, we come to the scripture in Colossians 1:15-17 which speaks of Jesus as being the firstborn of all creation and about creation in general:
(New World Translation) : "He is the image of the invisible God, the firstborn of all creation; because by means of him all [other] things were created in the heavens and upon the earth, the things visible and the things invisible, no matter whether they are thrones or lordships or governments or authorities. All [other] things have been created through him and for him. Also, he is before all [other] things and by means of him all [other] things were made to exist"
The above scripture with the addition of “[other]” in several places supports and leads one to conclude that firstborn in this scripture indicates first created. The logic being, Jesus was created first and then all “[other]” things were created by him as he could not have created himself.
This logic would be accurate if firstborn in the above scripture did in fact indicate first created. It does not. At the time in which Paul wrote the above scriptures, the Greek word for first created is proto with ktizo. This is not what Paul used when examining the Greek writings. Rather, Paul used the Greek word for firstborn with the indication of pre-eminence which is proto with tikto.
If Paul wanted to clearly indicate Jesus was first created he would have used the Greek word protoktizo; rather, it was not Paul’s intention to indicate such. Jesus is before all things in pre-eminence and Paul indicated that by using the Greek word prototikto.
The original writings of the scriptures did not contain the “[other]” placements as done by the Watchtower Society in their New World Translation of the Bible. Furthermore, it is not needed as Paul is speaking of pre-eminence and not of being first created. That is why other translations do not contain the “[other]” in the verses...
(New International Version) : "He is the image of the invisible God, the firstborn over all creation. For by him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things were created by him and for him. He is before all things, and in him all things hold together."
(New American Standard Bible) : "He is the image of the invisible God, the firstborn of all creation. For by Him all things were created, both in the heavens and on earth, visible and invisible, whether thrones or dominions or rulers or authorities--all things have been created through Him and for Him. He is before all things, and in Him all things hold together."
(New King James Version) : "He is the image of the invisible God, the firstborn over all creation. For by Him all things were created that are in heaven and that are on earth, visible and invisible, whether thrones or dominions or principalities or powers. All things were created through Him and for Him. And He is before all things, and in Him all things consist."
(Young's Literal Translation) : "who is the image of the invisible God, first-born of all creation, because in him were the all things created, those in the heavens, and those upon the earth, those visible, and those invisible, whether thrones, whether lordships, whether principalities, whether authorities; all things through him, and for him, have been created, and himself is before all, and the all things in him have consisted."
Indeed, the Watchtower Society is adding to the scriptures to support its doctrine and teaching that Jesus was created. That is not what Colossians is stating. Jesus is the pre-eminent one of all things. The Watchtower Society should not be adjusting scripture to fit their doctrine and teaching. They should be adjusting their doctrine and teaching to fit scripture.