Thanks lemonlau36.
The last topic we covered in theory is actually the use of nonchord tones in relation to harmonic progression!
I believe what Carl is saying is that there are "wrong notes" for lack of a better term. Pitches shouldn't be classified as right or wrong since it invades artistic integrity, but that's a different topic. However, there are notes that when played in certain harmonic contexts, they sound bad/dissonant.
In tonal music, you generally want notes that fit into some type of triad or 7th chord, while following a somewhat typical progression. More contemporary music pushes those boundaries with great results, but not to the extent where your average person will find everything aurally pleasing.
With the song (so far) that you have, your harmonic progression is actually pretty dece. Like, it works. What throws it off is you have non-chord tones in the melody that don't really resolve to the given key. Your piece starts in C major, moves to a dim7 chord, then resolves to C minor, then NCT's come in and it sounds... off, ESPECIALLY due to the minor 2nd created by the bass and melody. Electronic music can get away with it sometimes, but minor 2nds and augmented 4ths are intervals that almost always sound extremely dissonant unless it's placed in some sort of meaningful context. Since electronica tends to be tonal, that sort of interval sticks out more.
For example, at 0:07. That's the beginning of your 4-bar phrase. Your 4-bar bass pattern goes C-Bb-C-C, while your melody goes G---F---Eb---*Db*. Db clashes with C
Starting at 0:24, the melody is typically tonal again, but then it does another sort of modulation. Your second section goes G-F-Eb. Cool, Then Ab--BbAb--*Gb Bb C* Bb G... (repeat). The Gb makes it sound off, because the end of the phrase wants to resolve to G (which it does), but the Gb going to C (even though there's a Bb in the middle) is an augmented 4th (tritone) which is again another very dissonant interval in tonal music.
Essentially, you have two very dissonant intervals regularly occuring because they're present in four bar loops. Some people have different ears, so they might not notice anything "wrong" with what you've done. Harmony is a very opinionated topic.
Rhythmically, your song is pretty solid! 10/10. And if we've learned anything from Ke$ha, having a catchy beat is very important with dance music.