I really liked the art and the music. The boss may be a bit tanky, but I think my biggest issue is the lack of feedback given to the player when getting hit. Visual and/or auditory feedback for getting hit is pretty essential to the player's experience, especially in a fast paced game like yours. I had no clue when I was taking damage without constantly shifting my attention to my health. With the fight being so fast paced, it feels very detrimental to the gameplay.
As for the theme, you didn't really specify how you were interpreting the themes, so I'll interpret it lol. I think you did well with the theme because it definitely is missing everything a metroidvania has except a boss battle. Recurring dream fits in the sense that I had to play the fight over and over lol.
All that being said, you should really particpate in the SMVM. It sounds like you had a unfinished level already. And mechanics wise, I felt pretty natural except for the mentioned lack of feedback when getting hit. You could put out a well-polished demo or microvania in the remaining time you have.
Congrats on submitting!