"Firstborn" is the image of Jesus Christ, the first Man who was able to fully recognize and perfectly fulfill the Will of God, His Commandments, to express them in His Teachings and thus to find and reflect for the peoples the spiritual "Image" and "Likeness" of God. 

"Firstborn" is also a symbol of the spiritually-imaged "Israel" - the people who were the first of all nations to hear, to receive, to find the true knowledge, the fulfillment, the proclamation, of the Will of Jehovah God.

"Firstborn" is a symbol of the beginning of the knowledge and fulfillment of God's Commandments, of the primacy in the spiritual birth in oneself of a new man born again to a righteous life.