Rust fundamentally improves C++ with memory safety and allegedly provably correct concurrency. It is a vastly different set of assumptions, design, and opinions than C++.
What does Go do to fundamentally deviate from Java? IMO it is basically the same space with a few different opinions. It has GC, is C-style, a more modern stdlib than C/C++.
Go improves on Java in several ways, perhaps most importantly, it is much nicer to deploy - no JVM. It's also a lot less verbose, compiles way faster and uses composition instead of inheritance. Having said that, I really hate Java, and only mildly dislike Go.
What does Go do to fundamentally deviate from Java? IMO it is basically the same space with a few different opinions. It has GC, is C-style, a more modern stdlib than C/C++.