The Treasury of Daily Prayer notes that while some modern theologians believe St. James to have been the child of Joseph and the Blessed Virgin, throughout most of the Church (historically and even today) the title "brother" is taken to mean kinsman. St. James is the author of the epistle bearing his name in the New Testament, where he humbly refers to himself a "slave of Jesus Christ." Josephus recounts the story of his martyrdom in A.D. 62.
Pr. Gregory Wismar has penned a stanza for "By All the Saints" in honor of St. James of Jerusalem:
We sing of James, Christ's brother,
Who at Jerusalem
Told how God loved the Gentiles
And, in Christ, welcomed them.
Rejoicing in salvation
May we too, by God's grace,
Extend Christ's invitation
To all the human race.
The stanza has in mind the role that St. James played at the great Jerusalem Council, which he presided over, together with St. Peter and St. Paul.
The collect for this day asks that "we may follow his example of prayer and reconciliation and be strengthened by the witness of his death."