What does it mean that Jesus is firstborn over all creation and the only-begotten Son of God? Firstly He is firstborn over all sons of God. Like any firstborn, they are born before any other sibling exists. The Son of Man was born before any of the angels so when He was born they did not exist and when they were born He already existed. He is firstborn of creation too which means when He was born none of creation existed and when creation was born He already existed. So He is over creation as firstborn over it because He existed before it existed because He was born first. He is firstborn from the dead because when He rose there was no immortal raised from the dead and when anyone else is raised to immortality He is already raised so He is over them as a firstborn. This I’m sure is what it means. A firstborn is greater due to preeminence and has a kind of superior rank while still being one of the siblings. That is the significance of being born first. John the baptist was born before Jesus physically, biologically but proclaimed that still Jesus is preeminent over him having existed before him. He knew. He, the Son of Man, is before all things and in Him all things hold together.
Since the Son of Man is always and always will be preeminent by preexistence, the resurrection to immortality of anyone could not happen until first it happened to Him. And now it has, so now it can.
