Well that clears up everything. NOT.
TL;DR: as a musician and/or composer, don't over-think theory.
Duke Ellington (no slouch in the theory department, that's for sure) said it better than me: "There are simply two kinds of music, good music and the other kind. The only yardstick by which the result should be judged is simply that of how it sounds. If it sounds good it's successful; if it doesn't it has failed."
Point being that if you're diving so deeply into the weeds of theory that you're quibbling about whether to count Db and C# as different keys on an equal-temperament instrument in an attempt to make better sounding music, you're doing it wrong. If you're studying theory to understand why music that sounds good sounds good, now you're on the right track, and that theory will serve you well as a writer and a player.
I'm not saying theory is over-rated. It's critical for composers and improvisers to have working knowledge of melody, counterpoint and harmony. But ultimately what you play or write just has to sound good, and you don't have to know any theory to know if you've got that.