Ok, first of all, huge congrats on getting to the final attack, you're definitely officially the closest person to beating the whole game (that I'm aware of)! Just to possibly save you some frustration/confusion, there's sadly a lingering hitbox issue with the final attack that might prevent you from finishing the game properly (you might be able to squeeze through as long as you have more than 1 HP at the end), and Unity also will not end properly after beating all 3 sub-bosses (forcing you to load a checkpoint). Huge apologies for these and other issues, which I will definitely be uploading a fix for as soon as the voting is over!
Second of all, you've no idea how happy your kind words made me! I really tried to give each boss my all, especially ??????, while halfway expecting no one would even come close to seeing all the attacks. So, it makes me happier than I can even describe to know someone was willing to put so much time and effort into my very flawed and unfinished game.
Third of all... I agree 100% with pretty much all of your criticisms, especially regarding the (lack of) music and sound design. As soon as saw the 6 themes, and with what became Python, Rust and ?????? basically having already been planned before I even knew the themes, I was pretty much immediately locked into the idea of making 6 bosses for the 6 themes. But yeah... In retrospect, it absolutely wasn't a wise decision to try to make 6 in-depth bosses for a gamejam, and basically everything else took a back seat to trying to actually get those bosses to function at all.
On the bright side, I am planning to resubmit the game to Super MVM, and hoping to fix those issues as well as add some other things that just barely didn't make it into the gamejam version!
As for the controls... I guess they really are subjective, because I feel about W being the jump button exactly how you feel about spacebar, haha. I guess there really is no escaping the simple truth that this kind of game demands a control customization menu, which is another thing I will try my best to get into the final version! (along with the option to make slow walk a toggle)
As a fun fact, I wanted Unity to have a "desperation move" too, but being so short on time I decided to prioritize ??????'s. Definitely something I will try to get into the final game though. Also, if I ever got around to making achievements, having all 3 Unity members active at the same time (and at high health) and winning will definitely be one of them! ;)