I beaten the boss and die to some ranged attack tree I guess.
First of all I don't think you're game have anything to do with the theme of 'failure'. And you didn't explain it in the description too so I'll just skip this one.

I think what kind of game you're going for is some type of Metroidvania rpg I guess.

Okay now lets talk about the game :

1. Chores mechanics :
Exploring aimlessly and killing tree could be fun, like in hollow knight. But this game doesn't have lots of time, so I would discourage you from making a Metroidvania in a 78 hour game jam. Also if this is a Metroidvania game, then there isn't upgrade that I have found. You seem to put quite lot of effort into the boss so might as well make it a boss fight game. Other than that I'm fine with the core mechanic.

2. Combats :
The combat in this game is very very confusing. When fighting the tree, I don't even know I am taking damage untilled I look at my health bar. There should be more indicator remind that I'm taking damage. Like in the room with psychic tree killing me, I didn't even notice I was dying untilled I die. Also when I first playing, I have no idea I can kill the tree for corn. It would be nice to have some indicator that the tree is taking damage, like changing its color for a brief period, sound effects, etc( I notice the psychic tree have sfx but not regular tree). The boss is also very confusing. I think a lot of people don't know that the boss takes damage, so I would again recommend adding boss bar. Personally I don't like the design of getting slow down when releasing range attack. I feel like if you're getting slow down when doing range attack it should be slow down at all the charging time, but this is up to your design.

3. Art/Polish
Your art/animation is very good. I think the tree in the boss room with the tongue attack is a bit weird but that's all.
The polish is kind of poor. There isn't any kill effect, damaged effects or taken damage effects. The UI is also a bit buggy with the health bar not showing the correct percentage of the actual health. I notice the effects of getting hurt and range attack is the same, which is an issue because I have no idea am I taking damage or doing damage. I'm not a big fan of the leaf, but I guess it does add to the environment. I like the little detail of trail of snail. 
I feel like the background environment art and the actual enemy, player, etc sprite is very different in style.
with the player/enemy being cartoony detailed art vs the background/ui with simple/ brushes art.
In the first room It's says "click for next room" which confuses me because you're to press 'e' to go to next room. So I was stuck there for a bit. 

4. Sound effects/Music
I'm not very into music, but this music feel alarming and kinda epic. It feels like you're in dark soul final boss, fighting with the boss that could take you hour to beat. But in this game, most of the time you're exploring so I would disagree with the music design. The music is also very loud so I would recommend adding a setting to change music volume/mute. I couldn't hear any attacking sound effect, so I sometime hear but not all the time. I think the charging of the range attack sound effect definitely could be improve. And I could not hear any releasing range attack. Taking damage sound effect is very least alarming which my be why I didn't know I was taking damage.

OVERALL :
metroidvania for 72hour game jam is what I disagree with. And I see attempt to polish the game. 

Could not click to the next level. UI issue maybe?

Hi, which button do I need to press to exit the first room near the vortex?

Could you please add the list of commands in the game description.