Thank you for the feedback. I also noticed the hearts were not subtracting and that is a problem I aim to fix. Had to publish this project because it was 10 minutes before the deadline and we were calling it done for this project.
The player blinking white should be an indicator that you got hit.
As for the weird projectiles coming from the right, that was just poor last minute game design on my part before I had to publish the project. I wanted to spice up the game because I felt repetitive patrolling slimes would have bored the audience.