It seems like an actual long demo with lots of unfortunate glitches/bugs.
Not sure how to reproduce this but the room transition right before enter the room with first save point you encounter after game start actually made the game softlock then freeze as I was able to also input an attack. Settings menu is great, except for the fact that you can bind multiple keys to one function, Pause and Quit menu function should work on a single key(i.e ESC as it's a bit confusing to have them separate and have the pause key be the exit function on the quit menu). The game remains on a always-on-top state if you disable pausing when game loses focus, please remove that. Enemy insects(basic purple ones) can glitch out through walls and terrain to 'teleport' behind you and attack. Can't obtain the free leaves if I kill the monsters out of order on my way to get the roll/dodge item. Blue jellyfish sprites glitch out in overgrown jungle after wrapping them in webbing and are then impossible to strike or wrap them up until you walk under the sprite for it to reset. Enemies continue to walk and attack as you pick up an amber heart. Just loaded an empty cell where I was underwater, paused underwater and I kept losing oxygen and then health, both hitting 0. Tried exiting, it's impossible since the game wants to give you a game over screen over the pause menu so I'm stuck there and have to quit and reload as seen below.
Another thing is I initially went the wrong way and apparently rushed to the mantis boss fight with no way out, as the breakable shields just respawn after reloading a save file.
That shouldn't be blocked after a reload, should it?
Walls should be able to pick up on webbing easily even if up close.
Another hidden entrance that can get you stuck if you jump over to the right as you can't climb from the red marked terrain on the bottom 'inside' wall.
I don't know how you're doing game cell/stage/map transitions but the current one will end up getting you stuck like so, all because I entered from the 'wrong' side. It being somehow dynamic would be swell(i.e entering a different cell mid-air would transition with me still mid-air).
Somehow you can also get stuck after launching yourself with some momentum from web swinging, I don't think I'll be able to even finish this demo. Managed to backtrack using a glitch lightspiritdev pointed out, it was the only way possible to backtrack as neither of the bounce pads actually give you enough height to allow you to go back and defeat the Mantis boss and until I managed it, I was effectively in a game over state and had to restart. Found also another area that has absolutely nothing in it and made me fall through the entirety of the map.
All this hammer glitching is killing my fingers, please no more areas like these. I finally found the last connected area which has an invisible sign warning the adventurer to be prepared before going to the mountain range and the two rooms are unfinished. Can't kill the magma worm either so I guess I finally reached the 'end' of this demo.