> overwhelmingly driven by existing large enterprise codebases
That happens with all mainstream languages, but it's a feedback cycle. The more popular a language is (in large enterprise codebases), the more it will get used in new projects, for obvious reasons. People want to get shit done and to have good ROI and maintenance costs. Therefore, the availability of documentation, tooling, libraries, and developers helps, in large and small projects alike.
And yes, Java is quite fresh, IMO.