Extremely fun level design, really, you have a knack for that.
Now, I'm gonna give you some solid advice you might wanna take to heart - sometimes certain aesthetics in writing don't pan out. In this case, the writing on the wall just feel forced. And this is coming from someone who writes stuff like this all the time, but you need to make sure the context works. In this case it just felt off. It felt more like "generic indie emotional writing" that actually took away from the atmosphere more than anything else.
An immediate fix would be, imo, to make it more of a character monologue between levels. Really build into it. Forget the whole "there were people here, ominous sentient ancient words that change whenever I'm around" schtick and give the character an actual voice before the end of the game. That way, you actually got a build up into the end.
If you DO want to build a lore for what happened at this temple, put some murals on the wall or something. If you want a fantastic example of temple world building, I'd hit up the La Mulana series. But honestly? This game doesn't actually *need* that. Just keep it personal, give that build up, and you've got a something.
Otherwise, lemme just say, I really did have a lot of fun with this game. It wasn't particularly hard, some bits were a bit frustrating mostly because of the spike hitbox on top felt a little wonky and the character felt too slidey, but otherwise this is really solid, really good, stuff. I encourage you to keep at this.