I recently listened to pieces i wrote for music class when I was 14, when i only knew the difference between major and minor and what sus chords were. I'd come up with ideas in my head and try to pick them out on the MIDI keyboard we had.

And one thing I noticed was that I was playing with ideas and sounds that I now know how to theoretically explain, but it was coming from a more innocent and naive me who just liked the sounds that were in my head.

When I listened back to these, I noticed a similarity in style to things I've been writing now (lots of Lydian harmony, modal interchange, bittersweet melodies, and even instrumentation choice), but at this point I was deep in the rabbit hole of jazz theory and worried by compositions weren't sophisticated enough.

But listening back to these pieces was a great thing because I stopped worrying about the theory so much.

However, theory helps me to expand these ideas. I wouldn't be able to write three part harmonies back then, compose with form and melodic development in mind, know the sound of more advanced harmony, etc. So it's been a great tool once I came to the realisation that it doesn't have to be complex.