Thank you for such a nice review.
To be honest, before creating this game, I did some research on level design. I looked at the analysis of popular games, how they work from the inside. One of the sources talked about Celeste, namely about its music. So one of the features that makes Celeste more enjoyable is its music, which does not end even when you die or pause the game. This makes for a more enjoyable experience and leaves the player less frustrated.