It's all binary at the end of the day.

It’s all just energy moving around

On sand.

And those turtles that go all the way down lay their eggs in that sand.

That doesn't address the implications of something only working with JS at all.

The most popular JavaScript engine (V8) is written mostly in C++. Same with WebKit. Other JS engines are written in Rust, like Deno or Servo (used in parts of Firefox).

I'm not aware of a major Javascript engine which is written in C, except for QuickJS, which is not "major" in any sense of popularity but is an efficient engine for embedded use cases (and anything from Fabrice Bellard is always work a look).

I suppose C++ is written in C. In similar relationships like Typescript and Javascript.

Not really, no.