From what I have seen, there are two “contending” definitions for what is high-low level languages: one considers anything above assembly languages high-level, the other is less concrete, and would put for example managed languages into the high level category/towards that end of the spectrum, while C, Rust, C++ would be on the lower end, assembly even lower.

I prefer the latter definition, as the former is, while objective, quite useless. The second definition could be expanded by a partial order between languages by “feature X can be emulated in it” with some caveats[1], and then we might even get Rust/C++ beat C for low-levelness, since C don’t have any way to force vectorization (compiler-specific intrinsics don’t count!).

[1] since most languages employ FFI/linking, not even this definition is too specific — would probably have to write it as the “idiomatic language can emulate feature”