Consolidate/simplify site structure

Hijacking this issue because there's good content on it so far. Site structure needs needs to be revised to clearly segment user flow between 1) new users and 2) users that want to deepen their engagement. Structure should account for other infra like GitLab, and should reflect revisions to content

Original issue

The menu setup in this site is way confusing/convoluted.

Here are some ways in which this is confusing to users...

And for site maintainers it's also confusing because there are so many menus...

I think we need to come up with one menu for the public-facing site pages and organize all content into that that menu.