There are kids movies that nod to the fact that there will be adults in the audience by including winky references that fly over younger heads, or peppering the dialogue with pop culture allusions, or operating on some ironic double level. And then there are others, the rarer and more precious, that simply make the watching adults feel like the children they once were, all over again.

Swedish TV puppeteer and first-time feature director Petter Lennstrand’s unfeasibly endearing “Up in the Sky” is of the latter variety: a simple story told with such genuine heart, offbeat humor and unfakeable innocence that it feels like rediscovering a foundational movie from your own past, even as you watch it for the first time. It seems extremely likely that in a few years’ time, the kids lucky enough to have “Up in the Sky” in their lives right now will consider it a beloved classic.

As a narrative, it’s slight, gently nonsensical, and a little too easily resolved, but fleshed out with surprisingly affecting emotional beats, all reflected in the sweet, solemn, sad eyes of its wonderful star, Mira Forsell. She plays Pottan, a lonely little girl whose casually neglectful working parents are too busy to take much notice of her, their inattention bordering on cruelty when they accidentally leave her at the gates of a municipal recycling center thinking it’s the pony camp she’s due to attend.

Glimpsed on CCTV sitting hopelessly on her suitcase in a downpour, Pottan is reluctantly taken in by two of the workers: Shady escaped convict Dennis Crowbar (Adam Lundgren) and Ture, a doleful-looking old man with a scratchy voice who gets around on a mobility scooter and is also a puppet. Neither Dennis nor Pottan remark on that fact, though, and so the “rules” of this little world are established elegantly: Some of the characters are puppets, some are humans, but all are really just people.

The kindly Ture brings Pottan to see their (puppet) boss Rydberg — a scene-stealer comic creation, part Jim Henson’s Animal, part officious Will Ferrell character, voiced by Lennstrand himself. Rydberg is a boisterous but big-hearted tinpot dictator who, after establishing that Pottan can’t drive a forklift (which is cool because they don’t have a forklift) has “no salary requirements” and isn’t “in a union,” hires her on the spot.

The only proviso is that she doesn’t snoop about in the off-limits area where some scheme in is progress. Needless to say, the enterprising Pottan finds out all about it, and soon is central to its progress, which will involve wild coincidences, space travel, lonely rocket scientists, astronaut training, a docking sequence to rival that of “Interstellar” (not really), and an impromptu party scene at which the puppet animals of the dump play electro music on scavenged instruments.

Unlike many kids films in which there’s a certain bumpiness in how we get from moment to moment, as though it’s OK to hurry through certain bits because the young viewers will be too undiscerning to notice, Lennstrand’s film is a delight right down to the granular level. The burgeoning friendship between Pottan and the ruffian Dennis is delicately drawn, and the calm, crisp formalism of the camerawork from DP Erik Molberg Hansen treats the details of location and set design with respect. Despite what was no doubt a low budget and an aesthetic that makes a virtue of the lo-fi, the ramshackle, the assembled-from-spare-parts, every moment of “Up in the Sky” feels cared for, and built to last.

The subtitling will of course be an issue for very young children, which is a shame because it really feels like a film that can be enjoyed by kids of all ages. In fact, it may be the unusual case where one might advocate for a dubbed version: It is not overly wordy and the puppet characters could of course be re-voiced easily. It feels faintly sacrilegious, as the film’s off-kilter Swedishness is definitely part of its charm, but if it helps “Up in the Sky” reach the audience it deserves, maybe it’s something to consider, especially as it feels like no remake could ever really capture the same sincere sweetness summoned so effortlessly by this wistfully giddy one-off — lightning in a bottle rocket.