If you want to make this look a bit more realistic, maybe you could improve the textures a bit. Like maybe get a seamless dry wall texture from textures.com and add it to the walls with a normal map, and maybe something for the floor too. But this still looks pretty cool, it looks like it could be some kind of horror or story-based game.
To add to this as well, you could also tweak the lighting as well (broken lights, dim lights, lamps on the floor) to create the atmosphere of “horror”.
And also, try adjust your environment so it fits the tone/story you’re telling in your artwork. (Is this an abandoned art gallery? Is it a section no one dares to go in?) - Broken tiles, horror pictures, lighting as above all helps. Additionally, you could adjust the composition of your scene - What object is you trying to focus? Do you have a placement structure (What goes where?)? - That would help to draw us to the scene’s main element. (which is the shadow here).
Finally, do tell a story. (What happened here? What is the person doing here? How does this person feel?).
But, don’t let this discourage you in any sense. Keep working, keep posting updates and I’ll gurantee you’ll do better.