There are only 26 letters; there are only 12 notes; and there are only 9 kinds of lyrics.
They fit into the following categories:
1. We broke up.
Only nine archetypes for song lyrics! How amazing then that from such limited raw materials we keep coming up with new ways to say the same old things.
Ok, in all seriousness, I know there are many more kinds of songs than those mentioned above: social commentaries, protest songs, hymns, patriotic anthems, pseudo sci-fi spoofs about pooping into wormholes, and much more.