I like what's going on, and you have a pretty clear style. You have some natural talent.
Read the story now
Here are some suggestions:
Try to use less words. Sometimes you say some things in round about ways. Just go back through what you've written and look for places where you can simplify the language.
Continue to describe the characters. There was a lot of info on the first page, and I honestly couldn't take it all in. I don't remember which character is which or what they look like. I have no idea what your narrator looks like... Except maybe he has one eye and sharp teeth.
If you aren't already, use Grammarly to check your grammar. The last chapter needed a little more attention, and Grammarly will save you a ton of time, especially if you already have a good grasp of grammar.
This doesn't feel sci-fi yet. If the only sci-fi elements are going to be the extra dimensions, I'd call this fantasy. As far as I can tell, sci-fi readers are really looking for hard sci-fi nowadays, but this fits right in with fantasy so far. This will help you find readers who will be satisfied with your book after picking it up.
You're doing a great job. I really liked this hence why I actually read it... 😒 As opposed to pretending to do so. Keep the chapters short. Keep the story moving. Keep the reader informed. You really have a good foundation for the craft. Great job!