[dfan]

I admit that I do not have a quantitative measure to support my claim (as you note, constructing one is difficult). But qualitatively:

1) People have learned a lot from new engines: joseki (corner patterns), general strategy (e.g., moves on the side are now considered less valuable, making large moyos (largely empty space loosely surrounded by your stones) is less attractive because AIs have demonstrated that they're more invadable than previously thought) and are able to actually explain the new principles in human terms.

2) All go professionals now play in the new style, to some degree; ones who tried to continue in the old pre-AI style performed badly.

So I am comfortable claiming that human play has improved by learning from the new engines.

[selestify]

Is there a name for the new style?

[dfan]

I'm not aware of a single "official" name for it that everyone uses, like the Hypermodern style of chess in the early 20th century. In English, people say things "AI-inspired" or "AlphaGo style" (although a lot of the ideas come not from AlphaGo directly but from the public engines that followed in its wake).