I have to partially disagree with you here. You can write great code in JavaScript or Python. You can write exceptionally shitty code in C or C++.
While I agree with your sentiment that "serious programmers" should heavily focus on computer science fundamentals I still believe there's nothing wrong with starting with more accessible languages as long as you are willing to move on and are aware of the limitations of the technology you use and especially your own skill level. That is to say, gather experience and knowledge before you even think about handling people's money, regardless of which programming language you start with.
I agree with your first statement, for example Lightning App and Zap desktop clients are written in Javascript and Electrum is written in Python. Also, Node.js is widely used for servers, so it's very wrong to mark high-level languages and "useless for serious applications".
But I think it's actually more correct to start with basics like low level languages, information theory, computer science, cryptography and first of all math and then moving on to high-level languages. Because even if they abstract away from low level concepts to make programming easier, it's still important to understand what's going on under the hood to be a better programmer overall.