Or just what is a "song" anyway?
Since you ask.....generally speaking:
A
song has lyrics (however trite/minimal) which are
sung by a
singer(s).
If one calls their creative effort a
song I'd bet the vast majority of listeners will expect to hear a vocalist(s)
singing.If one is looking for ways to split hairs in this context have at it.

But....that's just me...to each their own.