Symbolism, Imagery, Allegory
Not every character can carry a tune, but you'll hear more than just a few ditties in these tales. We get to see competent musicians, as in "The Marvelous Minstrel," and incompetent musicians, as in "The Bremen Town Musicians." Rapunzel draws the prince to her with her singing, while the protagonist of "The Jew in the Thornbush" has a fiddle that compels anyone listening to it to dance as long as the fiddle is played.
Byproducts of music, such as dance, also feature in the tales. The princesses in "The Worn-out Dancing Shoes" are the ultimate dancing queens, sneaking into an otherworldly realm every night just to get their groove on. Lots of rhyming and rhythmic speech also occurs in the tales, as magical formulas, descriptive phrases, and pleas for help. Rumpelstiltskin reveals his name to the queen's hidden agent as he screeches a charming little rhyme about how he'll get the queen's child the next day. Song, music, and dance function as more than mere entertainment in the tales. They convey important information and literally make magic happen.