I think you have a good idea here, but I think there are some changes to be made to help it out. I think the monsters and humans should have predictable behavior, so that you can know when you need to block for each one. As it is now, you kinda just have to hope and pray that your monster shoots the right way and that the humans shoot the wrong way. There are a plethora of ways to do this, but it's really up to you.
It may also be interesting to add different human and monster types! Although that may have been too ambitious for you in this short time span.
Another minor suggestion is when you hold forward into a wall you can't go left or right, an easy fix I presume.
Overall, I liked the idea behind this game, but I feel like the execution is sloppy and needs some work. I also like the choice of music, and the artwork is cute.