I know very little about Norse mythology and even less about Thor as he’s depicted in Marvel comics, but that doesn’t seem to have hindered my enjoyment of the movie that bears his name. This is fun, straightforward stuff, closer in spirit to the earnest and enthusiastic Superman films than to the snarky, too-cool-for-school Iron Man films to which it is officially related. If the action sequences don’t have as much of the “wow” factor as they might, and if the whole thing has the anticlimactic feel of a movie whose real purpose is to set up another movie, those flaws are hardly significant enough to spoil the cheerful mood.

“Thor” is set in two primary locations. One is Asgard, the eternal realm that is dwelling place to the beings that the old Norwegians revered as gods. The other location is Earth, which I assume needs no introduction. Thor himself, played by Chris Hemsworth (James T. Kirk’s doomed father in the recent “Star Trek” reboot), is a mighty warrior, the son of Odin (Anthony Hopkins), and heir to the throne of Asgard. Due to his arrogance and over-fondness for war, Thor is stripped of his powers and banished to Earth. His big ol’ hammer, Mjolnir, which helps him fly around and wreck stuff, is likewise removed from his custody, hurled into the New Mexico desert where it made a cameo after the closing credits of “Iron Man 2.”

Now an ordinary mortal (albeit one with marvelous biceps and pectorals), Thor is befriended by Jane Foster (Natalie Portman), a wide-eyed astrophysicist investigating some kind of cosmic phenomenon in New Mexico. Her mentor, Erik Selvig (Stellan Skarsgard), grew up hearing legends about Thor, Odin, and the rest, and did not suppose that they were real. Their research assistant, Darcy (Kat Dennings), has absolutely no function in the story, but she’s good for comic relief early on.

The film has a lot of solid laughs, actually, without becoming a cartoon. (The screenplay is credited to Ashley Edward Miller and Zack Stentz, both from TV’s “Fringe,” and Don Payne, from “The Simpsons” and “Fantastic 4: Rise of the Silver Surfer.”) Thor is courtly and respectful of women — he is a prince, after all — yet also a mead-drinking, enemy-slaying hero once worshipped by Vikings. You will be amused, for example, by the way he responds to doctors trying to take his blood, or by the way he requests a second cup of coffee at breakfast.

As the movie version of the Marvel universe continues to expand, the creative overlords are getting better at establishing continuity between, say, this and “Iron Man” and the upcoming “Captain America.” Coulson (Clark Gregg), the SHIELD agent who keeps popping up in the Marvel films on his way to the big “Avengers” meet-up next year, is on hand, and there may or may not be a cameo by another “Avengers” character. That kind of thing is a treat for the hardcore fans, and there are other details — like the fake name Erik gives Thor when he’s arrested — that I didn’t realize meant anything until I looked them up later. Crucially, however, the movie remains accessible for novices, and doesn’t revel too much in for-nerds-only minutiae.

Have I failed to mention a villain? Ah, yes. In my defense, so did the movie, almost. Thor’s brother Loki (Tom Hiddleston), jealous at being passed over as Odin’s successor, causes trouble, though I never felt like the stakes were any higher than they’d be in an average issue of an average comic book. It’s hardly the grandeur you’d expect from what is theoretically the first entry in a franchise. Thor’s Asgardian warrior friends, Volstagg (Ray Stevenson), Hogun (Tadanobu Asano), Fandral (Josh Dallas), and Sif (Jaimie Alexander), contribute their energies in an early battle with Frost Giants and later with a very tall robot-looking thing, but their “Fellowship of the Ring”-style camaraderie doesn’t get enough screen time to really breathe. Rene Russo, playing Odin’s wife and Thor’s mother, has almost no lines.

The director is Kenneth Branagh, best known for his Shakespeare adaptations. You wouldn’t know he’d never made a movie this effects-heavy and expensive before, and maybe it’s not that different from Shakespeare anyway, what with its brothers fighting for the crown and its threats of war and its exiled princes and such. Branagh is surrounded by talented production designers, cinematographers, and editors, too, which certainly helps. The scenes in Asgard are beautifully rendered and quite convincing — no small feat, given the inter-dimensional travel and other potentially goofy elements involved.

There isn’t much gravitas to be found here, and that’s fine. Not everything needs to be “The Dark Knight.” “Thor” keeps things light and inconsequential. It’s perfect for 12-year-old boys, or for those of us who need to indulge our inner 12-year-old boys for a couple hours.

B (1 hr., 54 min.; PG-13, action violence.)