u/ConversationWeird801

It really messes up with my brain when I am learning music theory. Why can’t we just call things how they behave harmonically? Not just how they literally sound like? Like, then why don’t we call a part of a melody going from F to C in C major suddenly a switch to lydian mode for the five notes? But we still say it is C major?

Also, when analysing a piece harmonically, how do I know if like some sonorities is either some G major susaddomit13 chord or idk F minor susaddomit15 chord inverted on a note? If they are literally the same notes? (I know these chords are not, they aren’t even real, I am just trying to convey my idea)

In my case, I can’t think of melodies for the love of God. I want to write contemporary choral music, but I can’t find a melody. What do I do?