The verb tense switches gave this a younger feel, that the person speaking is a child. The idea is good, but I am wondering if, ‘it came one day’ and the sequence fits with time travel.. there is the possibility that it has come before, and will come after, in different stages of its development.. which could make for a twisted tale indeed.

Explaining dimensional travel is difficult so bravo for attempting it. The verb tense was hard to read but I liked that the creature is learning to use its abilities.
Note: “something out of anyone’s understanding” would read better as:
“something beyond anyone’s understanding”

Multiple levels of existence always reminds me of the Bartimeus trilogy, by Jonathan Stroud; a good read if anyone’s interested, though its fantasy-based.