C++ is not that complex, and honestly it's one of the best documented languages out there. The semantics are very clear and you can easily decide to stick to a smaller subset of C++ if you don't like the advanced features like concepts, template metaprogramming, and class hierarchies (I would in general advice against OOP in C++, just as I would in any other language).
Ruby does a lot of magic stuff to help beginners. That means the semantics are unclear. IMO this is similar to how Apple optimizes UI/UX for first impressions to drive sales. The journeyman user is neglected, simple things are easy to do, but the most powerful features are missing for journeyman and advanced users.
I'm not saying Ruby is a bad language. Just saying that I have the opposite view. I too love to learn, but Ruby did not help me learn, it actively got in my way.
You can make a simple language without confusing semantics, see Go, C, python.
> C++ is not that complex
C++ is so complex that you can take 10 C++ devs, put them in the same room, and none of them will be able to read any others' code because they've each written it in a mutually exclusive C++ feature set.
>C++ is not that complex
Relative to what, exactly?
It is very hard to take a statement like yours seriously when even veteran developers continue to ship software with memory bugs that exfiltrate data and crash systems to this day.