Titanic Theme of Perseverance

From the outset, we know for sure that things aren't going to work out so well for the vast majority of Titanic passengers. So it's kind of (darkly) ironic that perseverance is a big theme in the movie.

Jack, in particular, is very big on never giving up, no matter how bleak things are looking—which is why he fights like mad to survive the sinking of the ship. Other people are tossing themselves off the side of the boat or hunkering down in their rooms and just going down with the ship quietly, but not Jack—he drags Rose around the ship trying to make sure they avoid going into the water as long as possible, and he gives Rose a pep talk about never giving up ever as they marinate in the freezing water, waiting for rescue.

And it's a good thing, since Rose has felt less able to push through life's difficulties. After all, she and Jack met when she was trying to work up the nerve to throw herself off the back of the boat. Ultimately, she gets the message and manages to survive the night of Titanic's sinking and live an amazing, adventurous, super-fulfilling life.

1. Narrative-wise, Rose and Jack end up in exactly the same positions they would have if Rose had just departed on a lifeboat in the first place—Jack's dead, and she's safe. So, why make us go through that extra hour of movie? Why was it important to the film's overall themes or messages?
2. Rose's ability to survive and flourish after Titanic basically depends on abandoning her mother, whose survival (at least in terms of finances) was in jeopardy. Does that diminish Rose's triumph at all, in your eyes?
3. Does the movie's emphasis on surviving and not giving up get undercut when Jack, you know, dies?

Cameron makes the movie go on an extra hour after Rose could have left in a lifeboat, but Jack still ends up dead, and Rose lives. His decision did nothing for the plot other than extend it.

Rose didn't end up dead when she opted to stay with Jack rather than go on the lifeboat—but she could have, and that willingness to stick with love over safety marks a big change for her character.