Greetings!

I like your imagery, but it seems almost excessive, like you're trying too hard. You need to trim down your writing. You use words that mean almost the same thing at the same time. It creates a redundancy and overload of information.

A few faint, pale shafts of light filtered through the cracks of the cave ceiling, casting a dim glow upon the structures below. ---> Pale light filtered through the cracks in the cave ceiling, casting a dim glow upon the structures below. [You don't need to say they are shafts of light as long as they pass through cracks. Light through cracks are separated, and it is also unnecessary to tell us how many. They're cracks. If they were large, they'd be gouges or cuts.]

The unknown construction glistened and glittered silver and white in the milky light, appearing to be made of some sort of glass or metal. ---> The buildings glistened like silver or glass. [Glisten and glitter are almost the same thing. Don't double the description. You also already said the light is pale.]

Shimmering strands filled the cavernous space, appearing beautiful despite their sinister purpose. The spider-like silk was skillfully woven into intricate shapes and patterns, and the strands closer to the floor and sides were dripping with milky, slimy fluid. One touch was all it took to adhere, and the skeletons littering the floor were a clear testament to the effectiveness of the trap. ---> Shimmering strands filled the cavern in intricate shapes and patterns. Skeletons stuck to milky globules dripping next to the stone. (62 words become 20.)

To be frank, such long descriptions do not impress me. You're trying too hard. A mature work contains only what is necessary and is the testament to a skillful writer. Don't try to sound like a writer. Writers who do sound, no matter how good their dispositions may be, like pompous teenagers. It is not mature. I am not insulting you. I am explaining why your writing is not as good as I know it can be.

Relax, visualize the scene, and describe it like you would to a friend. Start one place and go down. Don't include everything. In this scene, all that is important is the size, the fact webbing exists, and skeletons are stuck in sticky globules. Past that, you don't need anything else. Readers don't want to know everything. They want to fill in the blanks. Tell them only what is necessary to imagine the foundation and they will decorate it. That way, you can get on with the action, the truly interesting parts.

"… what do you want…?" the teen asked the creature, looking up at it. ---- The teen gazed at the creature. "W-what do you want?"
[Never, let me repeat, NEVER explain dialogue. If the character asks something in the dialogue, never add he asked it. It's redundant. If your dialogue cannot stand by itself, if it needs to be explained, it isn't good enough. You can get around saying who is talking by having the speaker do something directly before he or she talks. Have someone DO something. Character development is the heart of a story but it can't happen if there is no action. Action is the support the heart resides in. You need it. Use it as much as possible.]

You explain your dialogue almost every time someone talks. That is a bloody shame, because your dialogue amuses me. Explaining dialogue beats it to death with a stick and destroys any emotion or power it might have had. Don't abuse your dialogue that way. It saddens me.

Kittens cry when writers explain dialogue. XD

I know you're a better writer than what I see here. I can see the rough talent struggling underneath. Refine it and your work can shine. I know how hard refining is. It's like walking through the desert without water, but trust me. Every step pays off. This story is not worthless. It is a road. Every writer has a buried closet of things we don't want to see the light of day.

Look at it, study it, and improve upon it.

I look forward to reading more of your work.