Alright, i think there's some pretty big things needing to be addressed for this game man. I just wanna start off with some positives: It works, and if it's your first game you're releasing to the public, it's not the worst thing in the world.
I'm gonna give you as much constructive feedback as i can, and i hope that you understand that i'm not having a go at you, and i'm sincerely trying to convey issues present and things i believe you need to focus on.
ART: Firstly, and most importantly, you NEED to try and differentiate characters, simple shapes aren't going to cut it for a platforming hack and slash. Especially when platforms are also shapes similar to enemies; straight off the bat, i though the blue bracket was some kind of moving platform i had to jump into, and immediately i was hurt with minimal indication that i was. This is a big issue, you cannot have enemies that resemble you closely, and you can not have such a simple feedback for damage.
In order to improve on this factor, i would suggest immediately trashing your current sprites for enemies, and moving to something that would indicate it's an enemy (for example, using circles against squares, showing a distinct difference).
A BIG WAY to indicate an enemy as well, is the use of colours; using extremely contrasting colors will immediately indicate to the player that "THIS IS AN ENEMY", you've tried at least, by making enemies various colours, but with the presentation of it, you've given the bracket enemy a color we associate as calming and friendly (blue) rather than a bright or hostile color (red, orange, florescent yellow, etc.) by doing this, you've misled the player into a false sense of security, immediately.
GAMEPLAY: This is a big issue, and one not uncommon in many amateur games, you've indicated nothing but movement keys to the player at the beginning. That's an issue, especially when thrown straight into the action. You NEED to have some form of tutorial. Some form of easy, non-punishing way, to allow the player to grasp the mechanics, and understand the environment of the game you're presenting.
STORY: A typical thing with platformers is a sense of purpose; run to the other side, save a person, kill invading enemies, etc. The issue with your current game, is that NONE of this is indicated. I don't know why i'm here, what i'm doing, or where i'm going. That is a CRITICAL FLAW with this game, because it doesn't entice someone to try to play it, fixing this with messages, maybe a prologue cutscene/area, or backstory before going in, would really benefit any type of platformer/RPG.
AUDIO: Perhaps it is a bug, but i didn't hear a single thing, i didn't hear music, i didn't hear interactive audio, i didn't hear sound effects. That really destroys any possibility for immersion; a key factor with making an atmosphere, driving tension, allowing a player to believe character/environment interaction comes from the audio. So the absence of it really kills any possibility of the game immersing its audience, and generally comes across as lazy or uncaring.
Enemies: Other than what has been previously said, enemies also need to have a reason to being your enemy. Give the player a reason to want to hack them up, develop some type of adversity to them, or even more interesting, present the player with options on interacting with enemies, similar to Undertale. Just don't throw a player in and expect them to know what and who are enemies and why they are.
END NOTE: It's not a terrible game by my standards, it's subjectively ok for a first time attempt, but it definitely needs to be built upon before being considered to be a "good" RPG/Hack and slash. A major way to build upon it is to sit down, and understand what you want to achieve, and what you want the player to feel. If you just want to have a simple, A-to-B platformer, do a loose, and simple story, and use the previous criticisms to build one; if you want the audience to invest into your game their time, energy, and excitement, give it a purpose and some meaning to it. Small, short and easy games can become great if you give the audience something to connect with.