system
Given the following post, respond as if you're commenting on Reddit:
human
[Steven Universe] So, is the language, English, really just Gem?

Kinda like the whole, does the Doctor look human, or do humans look like Timelords, thing, if the Gem War happened about 5,000 years before English was even a thing, doesn't that mean English-speaking humans are really just speaking Gem?
gpt
Gem bodies are packed with all kinds of sufficiently advanced technology. They just automatically translate whatever they say for the convenience of dealing with lesser lifeforms. 

They're humanoid because "bipedal with thumbs" is an efficient tool-using shape across the galaxy. It's just an example of convergent evolution.