I don't follow your logic here. "Firstborn" means "preeminence", not chronology.
This identifies the problem in denominational Christianity today. This is a flat denial of the word of God. Thank you for not trying to prove that statement from scripture because you would need to deny other scriptures to do it. You are believing someone who has made up a new meaning for the word "firstborn" and you are not believing God. The fact that Jesus Christ is the firstborn son of God from the dead gives him the preeminence. He is the first to be born of the Spirit of God. He is the head of a new family. He is the Last Adam, he is the second man. God has taught us all through scripture that he cannot accomplish his purpose through the flesh.
The New Testament is God starting over and proving that he can and will accomplish his purpose through the Spirit. All men are dead spiritually, including Jesus Christ, if one accepts the definition of death as separation. The resurrection of Jesus Christ from the dead proves everything that God says and illustrates in the four thousand years of the Old Testament times because it is the Spirit who raises Jesus from the dead and quickens his body. It is a birth and makes Jesus a threefold man., body, soul, and Spirit, three in one and one in three. This is the image of God and it could not have been accomplished by anyone but God and by anyone but Jesus Christ and by any other means than by the power of the Spirit of God.
Rom 8:8 So then they that are in the flesh cannot please God.
9 But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
Every man born in the Old Testament times was born of Adam. They were in his image They were dead spiritually. Every man born of a woman, even now, are born into the family of Adam and has his image. This is where we insert the lesson of Ishmael and Isaac and see what God intends by it. We see that Abraham attempting to please God by taking Hagar to produce the promised seed only caused chaos. Ishmael represents humanity born of the will of the flesh. They do not have the Spirit and are unconcerned about God and his laws. But God willing to demonstrate that he would send his own son, illustrated it by promising that Abraham and Sarah, being past childbearing, will yet have a son. This illustrates the miraculous physical birth by God of Jesus Christ. Isaac, in type, is the first begotten son of God. Ishmael grew up to have his own family and was always the enemy of the family of Isaac.
Ga 5:17 For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would.
Joh 3:6 That which is born of the flesh is flesh; and that which is born of the Spirit is spirit. 7 Marvel not that I said unto thee, Ye must be born again.
Next among the 3 Patriarchs is Jacob, producing the family of God. He represents the Spirit of God in type. All the children through whom God gives his laws and accomplishes his purposes are born through this man. We can learn of the present work of the Spirit of forming the church, the family of God, by this man Jacob. He, like Isaac, was the second born son. God is teaching us if we will hear that there must be two births, one of the flesh and a second by the Spirit. This truth is illustrated everywhere in the OT scriptures if one has eyes to see.
All the doctrines and mysteries of the new testament are hidden in the types and similitudes of the OT.
Ro 15:4 For whatsoever things were written aforetime were written for our learning, that we through patience and comfort of the scriptures might have hope.
Mt 13:52 Then said he unto them, Therefore every scribe which is instructed unto the kingdom of heaven is like unto a man that is an householder, which bringeth forth out of his treasure things new and old.
2Ti 3:16 All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:
Isa 48:6 Thou hast heard, see all this; and will not ye declare it? I have shewed thee new things from this time, even hidden things, and thou didst not know them.
So, with that in mind, Jesus Christ was the beginning of a new work of God. It began at the beginning of a three day period of time called the last days. It is the last three days of the week ending on the sabbath of rest. The work that God is doing is finished at the end of the second day, which is the sixth day over all. Of course one will need to reckon a day as one thousand years and a thousand years as a day as God said he does, which very few even believe. This is a miraculous physical birth of Jesus Christ like Isaac's. The new week, which begins on the eighth day, or the day after the sabbath of rest, begins with the resurrection of Jesus Christ from the dead. This is actual fact and it is also prophetically typical of the outworking of God's prophetic program of restoring his order. Jesus Christ identified with Adam's race in his birth and in his death and died so that the dead men in Adam might live in him. He took away the condemnation of sin and he rose from the dead with life.
Continued next post.