Wow, this is probably the most comprehensive criticism I've gotten of the game so far, thank you so much! From the video and your multiple high scores I can tell you really gave the game your all, and I commend you for that. I disagree with a couple of your points but I feel your criticism of the game is very accurate and puts the general consensus around the game into words. This is gonna be a long ass reply so bear with me.
I agree that there probably should be grabbing considering how fundamental it is to many of the best belt action games but there's not exactly any throwing in boxing so it wouldn't make too much sense for the mc to do. I've been brainstorming ideas for a second character that's based around grabbing but I wanna focus on the game's core design first. Special moves will be coming as well, you'll just have to unlock them. I'm hoping to add destructible environments with HP pickups as well. I'll definitely have to work on telegraphing attacks and their range as well. I really wish I could implement a fullscreen option, I really do. Godot has not support for scalable vector art from the research I've done so I want to keep the illusion of it being vector art by only rendering it at its native resolution with pixel perfect scaling combined with AA baked into the art itself. This looks awful when scaled up so that's why I haven't included any screen scaling options. It's far from an elegant solution I know, but it's the best I could come up with for now.
I really disagree with your disregard for arcade game design. You're completely right about it being way too generous (that and the screens don't last long at all) but the timer can be a great mechanic that pressures the player and forces them to be efficient in their play. To reduce it to something that developers just put in to "munch quarters" is such a shallow interpretation of why those games were designed the way they were. This sounds like a cope, but the whole point of the game is to be as accurate to a 2000s flash game as possible, sound is gonna be crunchy and compressed and art isn't supposed to be the greatest thing ever. I know you say not to take it as a compliment but I'm glad the art looks like a 2000s flash game to a fault, makes it far more authentic.
A couple notes about the video you provided, I should be more clear with the language I use. I noticed you had "frame limit" turned on likely because you thought it locked the framerate to 60fps. It actually makes it 30fps to make the game feel like a flash game but I wasn't clear about that at all and I'm sorry for that. I have a lot of work to do to make it so the enemies aren't so easily defeated like how you demonstrated they can be.
Sorry for the incredibly long-winded response, I figured this may be a good place to address what are probably the most common criticisms of the game. I can't promise I'll polish it to perfection or make it something amazing because like you said, it's not a great foundation. Given this is my first time trying to program a complete product, this is more to get my feet wet in game design. It's probably just best to try my best with it but also move on from it sooner rather than later. No point in polishing a turd, so to speak. But thank you again for comprehensiveness and honesty, it's appreciated more than you could ever know. Sorry if my response sounds a little defensive.