The Mascot

The Mascot is a 1933 pioneering animated Ladislas Starevich film. It's a sweet, sad, heartwarming story that mixes stop motion animation with live action.

Senses of Cinema says,

Considering its strong correspondences to more recent films such as The Nightmare Before Christmas and Toy Story, it is not surprising that The Mascot has been one of Starewicz’s most widely seen and distributed films (particularly in the United States). Nevertheless, Starewicz is generally an under-appreciated figure in film, and more specifically, animation history. Until the early 1990s his films were very hard to see (despite early 1980s retrospectives at places like the Edinburgh Film Festival), many of them, including his opus The Tale of the Fox, long thought to be lost forever. In light of the subsequent new Golden Era of feature-film animation, and the critical reappraisal of so much American animation from Warners to Disney (not that far to travel really), it seems time for Starewicz’s work to be more widely appraised

Wild Realm calls it "simply a joy".