First mission (spoilers possible) (Metal Gear Solid 5: The Phantom Pain)

What the hell is going on in the first mission (prologue)? References to Moby Dick, Ahab, Ishmael, who are we playing for in this mission, and who is Ishmael?
Spoiler I only have a hunch that we are playing as Phantom Big Boss, and "Ishmael" is the real Big Boss. Am I thinking right?