There are still some problems with the build but I was able to play your game. Here's some things you can fix/improve on:
- Did you rename the executable? (You shouldn't do that) I had to rename the data folder to get the build to run. If you want a different name, change product name in project settings
- There were canvas scaling issues. You should select scale with screen size in the canvas scaler to make sure UI elements display at the same relative positions at any resolution.
- The game shouldn't quit when the player dies. It should restart or go back to the start screen.
- The jump height was too low and the hitboxes were sometimes inaccurate. I died a lot because of this.
- The player sprite (and parts of the environment) had unwanted coloured patches due to compression. In the import settings for your sprites, set compression to none. (as this is pixel art, exact colours are required)
- You could add background music for a more immersive experience.
Overall, well done for uploading your first game and working through the build issues. You will keep improving by joining jams and listening to feedback.