You might enjoy https://nim-lang.org/ which has a Python-like syntax with even more flexibility really (UFCS, command-like calls, `fooTemplate: stuff` like user-defined "statements", user-defined operators, term-rewriting macros and more. With ARC it's really just about as safe as Rust and most of the stdlib is fast by default. "High quality" is kind of subjective, but they are often very welcoming of PRs.
Anyway, to your point, I think a newbie could pick up the basics quickly and later learn more advanced things. In terms of speed, like 3 different times I've compared some Nim impl to a Rust impl and the Nim was faster (though "at the extreme" speed is always more a measure of how much optimization effort has been applied, esp. if the language supports inline assembly).
https://cython.org/ , which is a gradually typed variant of Python that compiles to C, is another decent possibility.
Anyway, to your point, I think a newbie could pick up the basics quickly and later learn more advanced things. In terms of speed, like 3 different times I've compared some Nim impl to a Rust impl and the Nim was faster (though "at the extreme" speed is always more a measure of how much optimization effort has been applied, esp. if the language supports inline assembly).
https://cython.org/ , which is a gradually typed variant of Python that compiles to C, is another decent possibility.