Obviously accomplishments like this are interesting for their own sake. But the really interesting question for me is, is there anything here, that is new, that can be used outside of tree-based games of complete information? (A much weaker question, is there anything new here that can be used in other games?)

Let's take the ability to match the best humans at various tasks. If we put doing long multiplication better than the best human at "1", and passing the Turing Test at "10", where is a Go playing engine? I'd say less than "2", but still higher than chess.

Much higher (but still short of general intelligence, obviously) would be beating the best humans at language translation, proving math theorems, or answering factual questions phrased in natural language. Then, if and when computers can write novels which you'd prefer to read over the best human author, now we're talking.

So I think, we don't need to worry about our humanity here yet, and we're not remotely close. Over less than a century we've gone from outperforming humans in arithmetic to outperforming us in things that are a little less like arithmetic but still discrete games modeled by trees and precise searches.