I'd say mainstream adjacent, like Lisp. There was once 80% penetration into the Fortune 500.
various Lisps have most, if not all, of the above features and much more mainstream use in the '80s.
One could argue that Smalltalk was designed in part to be a "Lisp for children." So of course, Lisps already had those features.
This is the first time I've heard that, do you have a source?
This is very widely known inside the language community and beyond. It's mentioned in many keynotes and talks by Alan Kay and others. You can go to the Wikipedia page and search for "children"
https://en.wikipedia.org/wiki/Smalltalk
Also, there's this article. Search for "children"
http://worrydream.com/EarlyHistoryOfSmalltalk/#smalltalkAndC...
In one keynote talk, Alan Kay stated that the design goal was to create a common programming substrate usable by everyone, from children, to hobbyists, to enterprise programmers, to researchers. Arguably, they succeeded.