If you look at ANSI Common Lisp, there is no GC support. It is not even mentioned in the standard. But the whole languages is designed to use it by default. C++ is designed to not use GC by default.

Lambdas/closures in C++ are a total hack.

I'd say C++ is a mid-level language with lots of emulations of high-level features. The integration of closures into C++ is an example of that. Just by integrating a high-level feature poorly into C++ does not make C++ high-level.