Moreover, James declares himself a "slave" of Jesus Christ, but makes no mention of being His brother or about being a son of the Blessed Mother. Jude also says he is a slave and the brother of James.
The Lord NEVER violated Judaic law. On the Cross, He entrusted His Mother to John, had there been brothers this would have violated the law.
Which law?
The people surrounding Jesus feared for their lives. They ran and abandoned Christ. They thought they would be next. I believe James, Jude, Simon, Joseph and others all abandoned Christ in His time of need. Peter certainly did. All the Apostles ran. Mary did not run. John was there. Mary was alone at the foot of the cross and her other children were in hiding. Jesus entrusted Mary to the one who did not abandon him. Jesus saw those who followed him as his true mother and brothers and sisters. He gave John the responsibility of caring for Mary. John was Christ's brother in spirit. The others were as of yet unconverted.