Good luck with the KS
It's probably too late to offer feedback on every minute detail of the demo, so I'll just say I liked it overall and I think it works better than older versions I seem to remember, though I'm not convinced by the overall weightless feel (the jumping, for instance, or the way dialog appears - many small details like weight, recoil, stuff that feels reactive to player input, here it all sorts of "slides" with little impact - out of desperation I'll refer to Tim Roger's notion of crunchiness here, as I really have no better, but especially for a beat'em all, I think this notion is really key).
One thing that sticks out to me is the amount of available inputs: I feel it's too much, and you could/should reduce the number of available functions to fewer keys. For instance, I find little purpose in a separate interaction key - older beat'em ups have "interact" coupled with the main attack key, which works just fine. The other downside is that many of the keys feel underused: once you're grabbed on to someone, for instance, I found only the attack key to do something, with the directional arrow changing the effect. Same thing for jumping, dashing, etc... Here, your number of available buttons make us want to try every combination, but very few have actual effect, even though you have a wide array of moves. Reducing the number of inputs would make the character feel more reactive and able, and the player more clever for figuring out the "combos", even though they'd really be only two button presses at most, and you'd still have the exact same amount of moves.
A tengential point is the grabbing mechanic, as I'm not convinced it needs to be attached to a key - again, referring to older beat'em up tropes here. Most I can think of would automatically latch you on to an enemy upon contact, which makes for a more fluid experience.
(disclaimer: I played on keyboard, I'm not sure if the experience is different on gamepad, but I'm pretty sure I'd say the same thing)
I understand if it's too late to change many of these, but I still hope it might help to bring them up all the same, just in case, now that I had the chance to get a feel of your design for myself, not just through videos but actual play!