You know, most animals that sing just do so in order to defend territory or attract a mate. Humans and a few other animals do it just for fun but a lot don’t.
What if, following the humans are weird thing, most intelligent species in the universe either don’t sing or just sing to flirt or start arguments so when they encounter humans they’re really confused.
Like? They just sing randomly? They actually plan out their singing and there are humans that train for it and make careers out of it? The humans use singing for teaching and expressing emotions other than lust or aggression?
And humans sing in order to remember things easily, lull other humans to sleep, calm themselves down, express every emotion they might have, and even more. And all of this is so confusing to the aliens.
And then you have the musical theater weirdos who actually do use music for combat…
DarkestElemental616 