Hello fellow developer !
Overall fun :
It is the beginning of something. This is a good attempt for a training
Art/Graphics :
Style looks consistent but you need far more love on the main character to stand out a bit more.
Environment - Need to check the black and white thumbnails of concept art environment to understand how to bring back / forth elements in your landscape. Black tend to be more in front for closer elements, white for far ( atmospheric perspective )
Controls / UI
Decent it works, careful to put more emphasis on the hit effect, I did not understand I was getting hurt at firt. The shooting mechanic is buggy needs more work. Graphically it's alright and consistent.
Sound/Music
Go for something that has less presence if you do not have much experience in music, more subtle.
Keep it up !!