Main Man Meaning

(informal, idiomatic, chiefly African American Vernacular) One's closest male friend.

Example: 1989, David Ritz, Barbells and saxophones
  Thanks to Aaron (my main man) Priest...
1993, Matt Cohen, The bookseller
  "Dungo," Henry would say, "you're my main man." He would pronounce these words in front of Jeanine, or even strangers.
2004, JazzTimes (March 2004)
  As Moody says of his main man, "Diz influenced me from every standpoint. He was a friend, a father, a confidante, just everything to me.