Mozart’s the Magic Flute is largely a metaphor about the Freemasonry and the Enlightenment augmented by crude jokes.
Traditional music is a general description of old songs, often transmitted orally, sometimes belonging to the public domain.
The song “Hail, Columbia” is one of several songs once considered an unofficial national anthem of the United States.
Stephen Sondheim can be considered “the father of the modern American musical”. Sondheim evolved the traditional American musical instead of adopting the more contemporary style of his peers.
Jingle Bells may be one of the best known Christmas songs, but it was actually published in 1857 as a Thanksgiving song titled “One Horse Open Sleigh”.
“Happy birthday” was copyright protected from 1935 until Sept 2015. During that time you couldn’t sing happy birthday publicly without paying royalties.