What difference does it make if he had half brothers?
I’ve never seen anywhere in the bible where it states that Mary remained a virgin following the birth of Jesus.
Seems pretty clear James was a half brother.
Galatians 1:18-19 New International Version (NIV)
Then after three years, I went up to Jerusalem to get acquainted with Cephas[a] and stayed with him fifteen days. 19 I saw none of the other apostles—only James, the Lord’s brother.
Galatians 1:18-19 King James Version (KJV)
18 Then after three years I went up to Jerusalem to see Peter, and abode with him fifteen days.
19 But other of the apostles saw I none, save James the Lord’s brother.
it says the Lords brother, nothing about half-brother