“firstborn son”. Exactly.
Also, “And he knew her not till”.
Since both Mary and Joseph knew that she was a virgin, why would that phrase even be there in the scriptures? KNEW HER NOT.......TILL?
And the ‘Mary born sinless’ invention; and her mother too?
Mary passed none of her blood into her child. The mother and child’s circulatory systems are completely separate, from conception through childbirth.
You wrote:
“Exactly.”
“Firstborn” did not imply later children. All solitary sons were called the firstborn if they were the firstborn. They didn’t have to have siblings. Anyone who has ever actually read the Bible would know this. See Ex. 13:2, Ex. 34:20
“KNEW HER NOT.......TILL?”
Again, anyone who has actually read the Bible would know...2 Sam 6:23, 1 Cor 15:25 and 1 Tim 4:13
“And the ‘Mary born sinless’ invention; and her mother too?”
No, not her mother, and it’s no invention.