Compilation speed. Production quality native code compilers for modular languages always compiled quite fast. Just as an example with Turbo Pascal 4.0 (the first version with units) you could "fix 1 compile error->compile->fix next error" in just a few seconds.
Static binaries. Something any native code compiler should be able to do.
Method declaration syntax. Goes back to Oberon-2 (1991).
Most of the other stuff is a refinement of previous Rob Pike languages Alef (1992) and Limbo (1995).
Some people use coroutines, cooperative threading, channels etc. for years. In fact, the whole Solaris OS threading model was build around some of these features.
Nobody really claims any of Go's features are new in any way. And yet, Go put them together in a fashion that attracts developers because it is put together in an absolutely easy to use way.
There's this wonderful comparison of Go and Algol-68, actually meant as "Go is boring" criticism, but it really shows that Go has all these exciting features that have been around for several decades, and yet nobody bothered to implement them, integrate them and popularize them until the Go development team did so.
Could you link the comparison ? Can't find it with simple searches.
About the "Go is boring" thing, I also tend to think of Go as a boring language... but no more than C or Java. I feel it more like a "new but not so much" effect which I found it disappointing. By no mean it imply that's not a practical and useful language. In the end, the project and the code-base count more than the language itself.
That was published just about a month or two after Go was first released, it contains syntax errors (like the placements of curly braces), and Go has moved on significantly since then.
