How does Moby Dick reflect real life?
The greatest attempts at realism and the expression of "the real" in the novel relate to whaling.
A good portion of Melville's long book is dedicated to documenting life on a whaling ship, exploring this commercial enterprise from the crew (and the jobs of each crew member) to the modes of storage to types of whales to the uses of different substances harvested from the whales.
Many chapters deal with these details without moving the narrative forward making them "documentary" material.
On a more thematic level, the novel reflects real life in its depiction of friendship (and the importance of friendship), showing how Ishmael and Quequeg help one another in various ways as a result of their friendship.