eh, okay
level designs were pretty linear, which isn't too much of of problem, but the enemies were too easy to kill. Just find a box and you can kill any of the normal enemies. So maybe have them be able to jump up on boxes to get you or even have them be able to destroy the wooden crates.(I think that you would be able to do that since I have seen the enemies jump over gaps to get to me.) The bosses were somewhat similar. They had only a few distinct moves and most of them were quite easy to dodge. So maybe more moves so that it isnt as easy to learn how to kill a boss. (I killed every boss on my first try)
I would say that the game is well drawn, but it seems like you got inspiration from alien hominid as your aliens look similar.