Superb polish and presentation, if a bit disjointed in level design at times. I don't quite see what possibilities the time mechanic is supposed to be adding to this game just yet. It functionally plays like a kaizo platforming romhack, which is not what you'd expect from the Castlevania presentation or Metroidvania genre claims at all. It seems you understand that yourself, judging by the inclusion of a Mario area.
Sorry to deliver the label of bad fortune, but in its current state this game is indeed a 2D indie precision platformer. Checkpoints are dressed up as rewinding the player and defeating enemies is dressed up as rewinding them, but neither thematic fluff has any substantial effect upon how the game is played. Areas look different, yet ultimately what you're doing all the way through is tiptoeing around death contraptions and rerecording segmented TAS adjustments.