Hi Roman!
My opinion regarding the first one: I can't really tell what the monster is. The interior seems okay, but the creature makes no sense. It seems deformed somehow, and the mouth doesn't seem in the right place. Also there is the awkward connection to the neck, assuming it has one, and no difference in values to flesh out the creature's limbs.
There is also the matter of reflected light: while there is very strong light from the top putting the planes of the forms of the creature's body which face downward in shadow, there should also be light reflected from the sewer/ tunnel walls which would light to a lesser degree those same plane aforementioned. This should, I think, provide for a variety of values that would make the creature's limbs if not completely visible, then at least recognizable.
Also, before you put in all the grey tones to blur the scene, draw the outline of the creature and see if it makes sense and if it is recognizable. Blurring a drawing doesn't make it mysterious, it just makes it confusing.
As for the second painting, and while a lot of people seem to do this, I think you should try to finish your drawings/paintings. Putting something off as a WIP is merely giving in to the fear of not being able to finish it right. I get that too. But it is better to finish something badly and recognize not only what you're weak at but precisely what you're doing wrong and what misconceptions you have of a form/object in you mind, and then replace those with correct technique. If you're not very good at hands then draw them the best you can. Then study and try to improve. You can look at reference pictures and use them to finish the paining. Never impatiently smudge an area, but take your time and draw clearly defined lines.
Imagine you were writing an essay or story in a new language you're still learning -- which is exactly what drawing is: a language for story telling using lines and values rather than words -- Imagine you've learned some of the basics of that language, but not all, and that you wanted write an essay. A few paragraphs in you felt tired or disappointed, and one more paragraph in you couldn't think of a way to express an idea. Now instead of stopping, looking at a dictionary, or a textbook, then writing on a scrap paper, and rewriting as necessary, you just sort of smudge things by writing somehtn dfkg, rixykaroud krooq lkjiitaa felkafu dafagdif lofig, dafigdf lsusdabnh dadidodooozzzzzzz....
If I am to give an advice that I think is most important, and I by no means imply I know all there is to know about art, but lets ignore that for a moment and assume I do know what I'm talking about; my advice would be not to smudge damn it!
If you reach a spot you can't draw yet, get you sketchbook, look for pictures online or at your own body, and draw them in the sketchbook. Once you've found something you can use then redraw it in your painting/illustration. Of course the thing you should aim for is to be able to analyze figures as a collection of interconnected simple forms and be able to draw anything form imagination.
Also, still concerning the second painting, the colour looks sickly and too pale. Mark Brunet (Cubebrush on youtube) published a video where he shows how to paint skin; take a look at it it's very well explained.
The neck seems too thick and the ear is too far off to the right.
Final advice: Learn to draw in line before dabbling in painting. Learn to draw the figure convincingly in lines and values and you will be a terrific painter.
Best of luck.
