system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How come we call our moon "the moon," but we name so many others?

Petition to rename the moon.
gpt
Because for much of human history, we were unaware that other planets had their own moons.  Ours was the only one that could be seen, so it got its own designation and was just "the moon."  

In most circumstances nowadays, it's obvious that when you're talking about "the moon," you're referring to the really big, visible object in the sky, so there's no need to say anything other than "the moon" or "Earth's moon."