Mannie is a man of many hats. He's a computer repairman, a revolutionary leader, and a husband to six wives. On top of all that, he also gets to be the first-person central narrator of the novel, and when you consider that The Moon is a Harsh Mistress is several hundred pages long, you know that's no small task.
Okay, you might ask, but what's a first-person central narrator, other than a clunky title to have on one's business cards? Fair question, and to answer it, we'll need to consider an example. Like this one:
He did that first week in May and I had to trouble shoot. I was a private contractor, not on Authority's payroll. You see—or perhaps not; times have changed. Back in old days many a con served his time, then went on working for Authority in same job, happy to draw wages. But I was born free. (1.14)
The first thing you'll notice is that the narrator refers to himself as "I" throughout. This I tells us that Mannie is a part of the story being told; he lived it or, to put it another way, he has firsthand experience with it. When the narrator is a part of the story like this, literature enthusiasts call it first person.
The central narrator part of the title informs us that Mannie will be central to the story. He'll be taking part in its events, and his direct actions will affect the outcome of the story. This is how we know Mannie is the protagonist, too, but we'll take up that discussion in our "Character Roles." section.
(Red Alert: Don't go thinking all first-person narrators are automatically central ones, too. They don't have to be—although Mannie certainly fits the bill. There are first-person narrators called peripheral narrators, of which Nick Carraway from The Great Gatsby is perhaps the most famous example. As the name suggests, these narrators are not central, but instead chill at the edge of the story.)