In short, James was the Lord Jesus half brother in terms of human standing. He was a disciple of Jesus and witnessed many miracles and heard the Word of God speak in audible voice.
There are quite a few arguments about the reality of Jesus having earthly brothers and sisters. Various sects take theological position based on human tradition, and the overly, particular attitude that Mary and Joseph had other children. The scripture it says that Jesus’ own brothers did to believe in Him. (John 7: 5) This is a spiritual pattern in so many lives of the prophets and people of God. The closer we are to godly people, the less likely we are to believe. (John 4: 44)
Jesus grace the care of his mother into the reliable and loving hands of the Apostle John. With God, the only family ties that really matter, are our spiritual ones in the bond’s of Christ. (Matthew 10: 37)
So we have this Christian believer, who now realises and loves Jesus as brother and Lord, writing to Gods beloved people with a clear teaching about how to live their lives for God. James does not overstate the holiness that God expects and where the power is found, for us to overcome in this world.
This is James’ letter to all the saints of God, scattered widely among the nations of the world. It is a challenging and wise letter, to teach and admonish us to follow God with a whole heart of faith and love..