I was thinking about this and thought that it would be interesting to consider who, if any, could be considered the main character when all three movies are put together as a single story. IMO, the three principles may be narrowed down to Jack Sparrow, Will Turner, and Elizabeth Swann. Each movie has them as the focus and their arcs are what drive the movies.

While everyone knows Jack Sparrow is who draws the audiences, as a character he does not seem to have that much growth over the course of the movies; he is more or less the same Jack Sparrow at the end of AWE as the others.
Will Turner could definitely have a case made for him, but his role reduction in AWE makes me doubt that of him.
This leaves Elizabeth Swann, whom when you look at all three actually seems to be the character with the story as the focal point in the conventional sense.

Think about it:
-She is the first character to appear on screen as a child in COTBP, singing the pirate song. She apparently yearns to be one herself and despite her "Pirates!" shrugs throughout the movies, she always winds up working more for them than against them. She also tends to lead them more often than not.

-In DMC she more or less becomes a pirate out of necessity to survive. She has tried being a lady of upper class, but that has fallen apart. She makes a lot of decisions and double crosses that are very characteristic of a pirate.

-In AWE she not only becomes a pirate captain, she is their "leader" so to say. Whether or not she kept the title for the ten years until she saw Will again remains a mystery, but I guess she did. (Was the island she stayed on Shipwreck Cove? That was the only place that seemed inhabitable for her. ) Also, my father and I both noted that she seemed to get a lot of screentime in this one, moreso than other characters.

Just my .02, anyone else who wants to offer an opinion may do so, as there truly is no definite answer.

I don't know. Will Turner's character made a pretty huge turn in AWE by becoming the captain of the Flying Dutchman. If anything, his character had the biggest change to his life - sheparding the dead to the afterlife and only allowed on land every 10 years.

It's obviously an ensemble piece, but, yes, of the three leads, Elizabeth would be considered the main character. She's the only one who has an actual character arc in the films. And, no, Will Turner's fate doesn't count as character development.

They all are. Will and Elizabeth go through some major changes throughout the series. Jack doesn't have major growth, but he's more of an archetype. Look at him as Indiana Jones on the high seas and you start to get a better idea of that character.

I picked Will for that reason. He's not the same character he was at the beginning, which was just a blacksmith's apprentice. He pretty much became a pirate which he hated too.

Jack Sparrow. All the storylines revolve around capturing/rescuing him.

I say Capt. Jack. He may very well be the best pirate I've ever seen.

He's not even the best pirate in AWE. That would be Barbosa. I did like Jack better in Black Pearl though.

Jack's the main character. Everything revolves around him.

Yes it became more of an esemble piece but I think its Elizabeth Swann, due to the first movie and her arc in 3.

I was paraphrasing CotBP:
[Before Jack steals the Interceptor]
Norrington: That is, without doubt, the worst pirate I've ever seen.

[after Jack steals the Interceptor]
Officer: That's got to be the best pirate I've ever seen.
Norrington: So it would seem.

Ahhhh...got it.