JavaScript was definitely designed for web development. Though, at the time web development meant a tiny bit of magic in an otherwise static html document.
The crucial distinguishing factor is that JS was made to animate a bit of text... on every device in existence, past present or future. That's the biggest difference between the web and native.
The "every device in existence" fails with node, at example, which has a different standard library, and every browser support libraries and even syntax differently (which is why we backport stuff with tools like babel)
Most of Ruby's life has been dedicated to web development.
The original use-case at birth of a language matters less, as programming languages are living things that evolve and mature, sometimes morphing into very different things than they were at the beginning.
Likewise Rust's current lifespan has almost entirely been dedicated to taking on C/C++ and their use-cases in systems programming and server applications. That's all that really matters here.
No, because PHP was not designed at all, it was just a hack that solved some problems and started to evolve. Anyway, web development in '95 is not the same thing as today.
So for web development, do you use PHP?
Because neither Python, nor Ruby nor even JavaScript itself was designed for web development.