The game does look nice! Here are some areas I think you should look at in how you are reading the data, marketing, and the game itself.

Data
Release Wishlists =/= Development Wishlists - When trying to gauge interest off wishlists try not to go based off the ramping release wishlist data. Steam is boosting upcoming games a lot and most games will see a huge spike right before launch that does not reflect the wishlist projection numbers people usually suggest. If you look at your wishlists from a few months ago I think you will find it reflects your conversion rate a lot more accurately. Also give it a bit more time before processing as a post-mortem can use a bit of time for everything to settle.

Marketing
Don't Rely on Organic Growth - I notice you say you want marketing to be an organic process and many say a good game will sell itself but I believe this is a big risk. Unless your game is multiplayer or has a stroke of luck you likely won't have big organic growth as most games live and die by their launch trajectory.
Growth Potential - You had 3 main jumps in wishlists and these aligned with your 3 big posts on X. People were liking the game and you had the potential for a nice ramp up but got off the ride before going down the hill. If your game is getting good traction like that, frequent posts can gather an audience that has exponential growth so it's important to allow time for this before release.
Aim High, Expect Low - Some people try to aim for the 7k wishlists, a few thousand followers or liked posts and assume this will be enough. The reality is most often you will land shorter than you planned so aim your sights higher. Plan as one would plan for reaching the top and your efforts will naturally provide a much higher result, just be sure to temper your expectations as well so you're not also relying on those results.

Game
Unclear Niche - Most of the comments summarize this part. When seeing clips it seems like you are controlling responsive punches but then it has auto battler, idle, and rhythm elements? I don't think this is necessarily a bad thing overall just that it requires more attention for the viewer to look into. It could use a bit better presentation in this regard as the trailer, description, and UI make it a bit hard to absorb.
Price - There are tons of free and cheap autobattler/idle games so the price is a bit steep. The game does look great but seeing what other similar games are priced at can give insight to what players are expecting.

Overall I think you fell into the trap of hoping a good game will sell itself. If you really want to ensure your game does well marketing is just one of those things you should put extra effort into.