Thank you for your writing, and submitting it to Manifesto Jam despite your reservations! I think it's very easy to get discouraged if you work hard on something and it doesn't get recognition. But from my own observations, not having people see your work is as much (if not more) dependent upon luck-of-the-draw than it ever is about craft or "talent" as you mentioned. The illusion of meritocracy runs deep!
What's helped me a lot is whatever project I'm working on, it has an element that delights me intrinsically, so that even if the finished product amounts to nothing, I still was able to get joy out of it. I think it also just takes patience and recognition that growth to develop your art doesn't happen linearly. Your line about having a period of inactivity really spoke to me, I definitely experienced that during the pandemic!
And hey, I don't think there's anything wrong with "aping themes" as you put it :) The phrase "Fake it 'til you make it" is quite pat but I think there's some truth there. Definitely when I've been at my most experimental and trying to push my boundaries, I've felt like I was in over my head or "too stupid" to explore something. But it pays off if you stick with it!