Jack is not a secondary character in Curse of the Black Pearl.
I see this opinion put forward that Jack is essentially a side character in the first POTC movie and it really makes no sense to me. I mean, yes, it’s true he doesn’t have the character development of Will and Elizabeth, but that doesn’t mean he’s not the protagonist. Everything about the movie tells us he’s the main character.
First of all we have bog standard screen time. Jack gets 44 minutes compared to only 35 mins and 31 mins for Elizabeth and Will respectively. Then in terms of driving the plot he’s vitally important as it all ultimately trickles back to when he was captain of the Black Pearl leading up to Barbossa’s mutiny. Will and Elizabeth ultimately grow as characters because of Jack’s interjection into their lives. Will’s story is the classic hero’s tale, yes, like Luke in A New Hope. But Jack isn’t the Han Solo character who doesn’t appear for the first 40 minutes, he’s involved in the plot at the 10 minute mark. So I really don’t understand why people seem to think he only became the main character in the later films because the truth is he always was.