What are some great songs from "unassuming places"?

Me and my buddy are trying to put a set-list together with the theme mentioned in the title.

"Unassuming places" is intentionally a little vague, but the idea is that feeling of "damn, I did not expect a song from this [insert piece of media] to be that good," or when you sit down and really listen to something you are surprised at well-composed it is, or songs that sound simple and reach a wide audience, but are actually a lot more complicated under the hood.

Some examples of the sounds we're going for are:

• Disney tunes like Someday My Prince Will Come and Bear Necessities
• Children's songs/show themes such as Castaways by the Backyardigans, or the iCarly, Arthur, and Flintstones theme songs
• Songs from Nintendo games (really the epitome/inspiration of this list) like KK Jazz and KK Bossa, the Eterna Forest and Littleroot themes, Hateno Village theme, or the Underworld theme from Super Mario Bros.

You might also be able to call this list "songs geared towards children but are actually good" but I feel like that has more of a nursery rhyme-ish connotation and I'm hoping to branch out of that.

We're a guitar duo with a jazz background, so songs that could potentially fit that mold are preferred, but I don't want that to hinder anyone from giving suggestions! I'd love to see what anyone can come up with.