There’s nothing inherently wrong with using a real-life tragedy — even one of the magnitude of the sinking of the Titanic, in which more than two-thirds of the ship’s 2,207 passengers were lost — as a background for a made-up story. But the story has to serve the event, not the other way around. And while absolute historical accuracy isn’t necessary, a filmmaker with some integrity (or at least half a heart) would try to maintain some kind of faithfulness to the spirit of the event.

It’s obvious, though, that Cameron wasn’t thinking in those terms. “Titanic” puts two lovers (Kate Winslet and Leonardo DiCaprio) at center stage and sketches in all the other details sloppily. We know that lots of people died — late in the film we see their bodies bobbing in the water, and we’re even treated to a dead-baby shot, but we have very little sense of the dead as real people. Every character — including DiCaprio, a third-class passenger who won his passage on the ship at the last minute in a poker game, and Winslet, a spunky upper-class teen who’s sulky because she’s being forced to wed a rich stuffed shirt — is a stereotype. The rich, in first-class, are all nasty and self-centered; the poor, in third-class, are all spirited and noble.

It’s pointed out that famous first-class passenger Ben Guggenheim is aboard with his mistress, and John Jacob Astor is introduced in a gossipy way. (His very young wife is obviously pregnant, and the ladies make it a point to cluck-cluck over that fact.) But the reality is that these rich, incredibly influential men chose to go down with the ship when they could easily have used their clout to wrangle a seat in a lifeboat. Cameron downplays their real-life nobility in order to further his own trite, heavy-handed view of the rich. In Cameron’s view, it’s not important that these men gave up their lives. What matters is that during their lifetime, they might have looked askance at you if you mistakenly picked up the wrong fork.

Cameron has little finesse, or originality, as a storyteller. The picture’s framing story involves an elderly woman (Gloria Stuart), who contacts explorer Brock Lovett (Bill Paxton) after she sees, on television, a charcoal portrait that he’s dredged up from the Titanic’s wreckage. It turns out she’s the woman in the portrait; she was the young Rose DeWitt Bukater (Winslet), and the drawing was done on board by Jack Dawson (DiCaprio). The two met when the depressed Rose tried to throw herself overboard and Jack rescued her. The love story here — save for the scene in which Jack sketches Rose in the altogether, which crackles with gentle, nervous eroticism — isn’t much to begin with, and it buckles further under the tiresome constraints Cameron packs around it. Jack and Rose face the disapproval of Rose’s mother (Frances Fisher, in an uncharacteristically stiff performance) and fianci (played by Billy Zane with all the liveliness of a shirt stud). The jealous fianci frames Jack for a jewel theft, and high drama ensues when Jack is handcuffed to a pipe by another upper-crust baddie just as the ship hits the iceberg and the lower decks begin to fill with water.

Somewhere in there, other people die. We also get to see the big ship pull apart in the middle, her rear half rising until it’s perpendicular to the ocean’s surface and then slipping into the briny deep — and somehow, not even that seems like a big deal. By this point, we’re supposed to care for the lovers enough that we can see them as a fitting center to this giant tragedy, a way of putting it on a smaller, more humanly manageable scale. But Cameron doesn’t know how to guide us to that kind of intimate focus. His canvas is so massive, you never know where to look, and when you look back over the whole, none of it looks like much — and this is the Titanic we’re talking about, the stuff of ballads and legends. “Titanic” sure looks like it cost $200 million — the sets and costumes are lavish, and the ship sure is big — but there’s no magic or poetry in sight.

That “Titanic,” at three hours and 10 minutes, is a crashing bore is a big enough problem. I could almost forgive the movie if it at least succeeded as a romance. But its two leads, both of them hugely capable actors, are undermined by ham-fisted direction and loads of blockhead dialogue. Jack gets stuck with lines like “When you’ve got nothing, you’ve got nothing to lose” and “You could just call me a tumbleweed blowin’ in the wind.” (The script credit goes to Cameron; shouldn’t they have added “Inspired by the words and music of Bob Dylan”?) Winslet fares even worse, straitjacketed with Edwardian-era psychobabble about “the inertia of my life.” In their scenes together, the two sometimes churn up a small whirlwind of charm, particularly since DiCaprio couldn’t be a dull romantic lead if he tried. Few other young actors know how to look at a woman the way he does. He doesn’t just want to see through to Winslet’s soul; he seems to want to ask it, politely but as if his life depended on it, if it would like to dance.

Maybe Cameron’s biggest mistake is that he never realizes that the ship itself can’t be considered a minor character, a giant prop for his piddling effort at epic storytelling. There’s a reason seamen refer to their vessel as “she,” and the Titanic, her famous and terrible fate aside, was something special. “There will never be another like her,” one surviving crew member told Walter Lord, the author of the 1955 book “A Night to Remember,” a scrupulously researched and elegantly mournful account of the tragedy, later made into a superb movie of the same name by British director Roy Baker. Baker’s movie is everything Cameron’s is not. (Although, curiously enough, it must have impressed Cameron, too — he lifts whole chunks of screenwriter Eric Ambler’s dialogue.)

Elegiac and crisply detailed, “A Night to Remember” zeros in on the emotional center of the Titanic’s story: It makes the lives lost actually mean something to us. But even beyond that, Baker’s movie, as well as Ballard’s footage and Lord’s book, all capture something that’s completely lost on Cameron. The ship herself is one of the most tragic romantic figures in all of history. Against all her best intentions she let people down. She didn’t mean any harm, and yet, after all traces of her passengers and crew are gone, she’s the one left sitting lonely at the bottom of the ocean. The last thing she deserves is to be plundered by the likes of James Cameron.