i'd echo what lydian said!
something that helped me improve in terms of songwriting and harmony is to try intentionally limiting yourself. think of how valuable sketching ideas w/ pen and paper is in graphic design, it's like that. computers are extremely powerful for getting our ideas out, but the abundance of choices can be paralyzing. the simple act of starting a project on computer vs. "traditional" mediums has an effect on your process, which isn't good or bad, just something to keep in mind. try sketching lots of song ideas out with simple pre-made templates (ask mussar about his methods for that), and worrying about production details later.
if that doesn't work, try limiting yourself to one instrument at a time, especially playing one physically if you're able to! i started learning piano this past year, and have spent a lot of time learning beginner pieces that only use two voices, like Bach minuets. from there, i tried writing a few pieces on piano with that same two-voiced rule, and i feel like those strict limitations really helped my sense of harmony and composition.
those "the clouds parted and this song idea came to me fully formed" definitely do happen, but they're pretty rare. a lot of it is starting with a small idea and stumbling into happy accidents. try to just have fun and mess around with sounds and melodies, let it take you where it wants. you can do it!!
