When I did the install of BP I followed this guide: https://premium.wpmudev.org/blog/buddypress-guide/ Initially, I was using another theme which required nesting the pages in order to make a drop down menu in associated groups within the header. When I installed the twentysixteen theme I did not remove that nesting. So, I ended up with up with that mess you found. By removing the nesting – which wasn’t needed – through Pages in Admin, all of the buttons have come back. The “Groups” page works wonderfully.
I was under the impression that BP was a plug-in that was added to WP through the use of the “Add” feature within WP. How would I do an install of BP “at the same level of WP”? As a plug-in, doesn’t it install within WP? Would it be necessary to do a reinstall of the entire site to get two, same level installs?