Yeah, level 3 will be a HLL. It just doesn't matter too much which one it is, or that it "rules them all". A single reasonably high-level language X is in practice superior to a basket of high-level languages, even if some of the languages in the basket are individually higher-level than X.
You're absolutely right that languages are only part of the problem. Beyond the language choice, Mu provides guardrails to help you pick up the underlying technical knowledge by just trying things and seeing informative error messages (often failing tests) in response. That's the hope, anyway.
Right now the first HLL is still in progress. I spent some time with a postfix-based language before changing my mind. Now I'm working on a Lisp-based HLL. So I'm not dogmatic about what the HLL should be, and in time there will probably be multiple options in separate forks/repos.
You're absolutely right that languages are only part of the problem. Beyond the language choice, Mu provides guardrails to help you pick up the underlying technical knowledge by just trying things and seeing informative error messages (often failing tests) in response. That's the hope, anyway.
Right now the first HLL is still in progress. I spent some time with a postfix-based language before changing my mind. Now I'm working on a Lisp-based HLL. So I'm not dogmatic about what the HLL should be, and in time there will probably be multiple options in separate forks/repos.