> I don't agree that it's somehow impossible to get things right and I'm not even sure you really believe that.
That depends what you mean by "things." Obviously, languages created in 2015 might fix mistakes made in 1985, and recognised as mistakes, in, say, 1995. But the things that a language needs to solve over its lifetime are mostly unknown when it's created. How the language handles the problems that are known when it's created is less interesting. If it doesn't do it well, it will never become popular. What's interesting is how it adapts when those problems change with time and new ones appear.
Take "explicit". In hindsight I suspect even many C++ proponents would agree that actually you don't want C++ conversion behaviour (when calling a function that takes a parameter of type X and you've provided a parameter of type Y, the C++ compiler will look for any way to construct an X that only needs a Y and then call that constructor rather than report that you've got the wrong type) by default. Perhaps C++ should have implicit conversion you can opt into, but it certainly should not have (as it does today) implicit conversion you must know about and opt out of to avoid blowing your feet off by mistake.
But I argue that it goes much further than such superficial mistakes. Multiple inheritance is a mistake. Personally I'm sold on the theory that all type inheritance is a mistake full stop (heritability should be a property only of interfaces), lots of people don't agree, but far fewer support the choice C++ made to embrace multiple inheritance of types. It's just so rarely even useful let alone the best option to solve a problem.