The heart = Liz Possible Spoilers
The heart in the movie was meant to resemble Liz..and Jack REALLY wants to be the "key to her heart" and not find the actual key itself. thats why his compass was pointing to her instead of the location of the REAL key. So by going to Tia he learns how to get the REAL key and in turn he learns how to be the "key to her heart"(tia helps him in both ways)
JACK SPARROW:
We're looking for this. And what it
goes to.(key)
TIA DALMA
The Compass you bartered from me. It
cannot lead you to dis?
JACK SPARROW
Maybe. Why?
TIA DALMA
Ayeee... Jack Sparrow does not know
what he wants! Or... do know, but are
loathe to claim it as your own. Your
key go to a chest, and it is what lay
inside the chest you seek, don't it?
basically meaning Liz...he wants to win her heart over but doesn't know how the hell to do it..and he's having trouble removing William from the equation..she says YOUR key and not THE key..she says A CHEST not THE chest..he wants to be the KEY TO HER HEART! THAT is what the compass is telling him...and I think he knows thats what it is..because he said "maybe..why?" and when she basically says out loud what he's trying to do he barly raises an eyebrow..he wants help in more ways than one..
Towards the end when Will comes back ..He HAS the key so he "IS" the key to her heart..but he's more concerned about saving his dad so he loses it to Jack. This moment resembles what HAPPENED in the movie..he wasnt there for her he was with his dad and Jack moved in on her and she started to gain feelings for him Then all three men fight for that key..Jack wins it and becomes the key to her heart (learns how to love her) and WINS THE HEART OVER.. he has the heart and when he sees Will trying to get at it..he viciously SMACKS HIM OVER THE HEAD with an oar...."dont touch Liz she's MINE!" which symbloizes how much he wants him out of the way when it comes to Liz.. Also symbolizes that he HAs won her over Will..
POSSIBLE SPOILER:
What happens next with the heart might be a hint as to what is going to happen in the next movie with Sao feng who works for the the EITC..Liz gets kidnapped by him apparently..and Norrington has a big part to play in that happening..Also apparently Jack foolishly gives her over to Sao feng thinking that she will be safe with him for one night and that he will see her again the next day..but finds out later that she Isn't safe at all..Jack foolishly thinks the heart is safe in the Jar. But when he realizes that its gone and that its not safe at all he is an emotional wreck.....
Now this is whats making me worried with what Disney might do with the love triangle..Jack realises how much Liz means to him once she is in danger in this movie..he goes to rescue her which is what he might do in the next one..she is greatful but she choses to save WILL..She accepts that she loves Jack..but choses to "save Will"..and Jack ACCEPTS IT and DIES so that they can be safe..So me thinks in movie 3. Liz might Accept that she loves Jack but choose Will to save Will from his "destiny"and Jack will accept the choice in movie 3 Basically a pity pairing..Jack calls her a pirate..she looks at him as if to say "no thats not what I want" and she runs off...so maybe she Will go back to a crappy life with Will 🙄
I hope to god Jack wont Die and do the honorable thing so he can save the Will/Liz's partnership..
If so thanks Disney for getting everyone hyped up with a Jack/Liz pairing and then spectacularyly dashing their hopes.. 😠