Jesus was the firstborn spirit child of the Father before the world was and Jesus is the Only begotten of the Father in the flesh and thus he is also the firstborn in the flesh and the firstborn of Mary as well. Jesus is also the firstborn from the dead.
Acts 17:28-29
28 For in him we live, and move, and have our being; as certain also of your own poets have said, For we are also his offspring.
29 Forasmuch then as we are the offspring of God, we ought not to think that the Godhead is like unto gold, or silver, or stone, graven by art and man’s device.
Hebrews 12:9
9 Furthermore we have had fathers of our flesh which corrected us, and we gave them reverence: shall we not much rather be in subjection unto the Father of
spirits, and live?
Revelation 3:14
14 And unto the angel of the church of the Laodiceans write; These things saith the Amen, the faithful and true witness, the beginning of the creation of God;
Colossians 1:14-15
14 In whom we have redemption through his blood, even the forgiveness of sins:
15 Who is the image of the invisible God, the firstborn of every creature:
Romans 8:28-30
28 And we know that all things work together for good to them that love God, to them who are the called according to his purpose.
29 For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that he might be the firstborn among many brethren.
30 Moreover whom he did predestinate, them he also called: and whom he called, them he also justified: and whom he justified, them he also glorified.
John 3:16
16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
Luke 2:7
7 And she brought forth her firstborn son, and wrapped him in swaddling clothes, and laid him in a manger; because there was no room for them in the inn.
Colossian 1:18
18 And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence.