Always weird to see people without any technical skills in programming-related YT channel comments lol. If you're jealous, start learning! Everything he showed can be learned within a few days of getting started.
Love your video. When I see this I think of my first coding teacher who always ask me : Why ? Why do you made that ?? And the answer is always… humm because I can !
What I really like about JavaScript is that in C++. You would have probably had to write at least four times as many lines of code just to get an image on the screen... [In other words, I like how JavaScript is very immediate language IMO That makes it really good for learning because you get instant gratification]
It's a friendly community and easy to get started with for canvas animation! But if you want to go deep into web development (especially outside of canvas) then HTML and CSS is great to explore!
j5js is a javascript library adding additional functionality to javacsript - html and css are templating/markup langauge for page layout and styling - javascript is a code your browser/machiene executes that can directly modify that page layout. comparing p5js and html/css doesnt really make sense