How do I link Pages in a hierarchy?

I am a newcomer to WordPress and creating websites. Got started using WP ver 4.3 hosted on BlueHost a week ago. I have minimal experience writing/editing HTML and scripting language, so I prefer to use existing capabilities in WP. I’m using the WP Twenty Fifteen theme for now.

My objective is to create an informational website (not a blog site) for a senior-living community. This will update and re-organize a long-used but obsolescent website created using Dreamweaver by another individual.

Desired characteristics of the new website:
* Usable by persons having minimal computer and browser experience, and possibly reduced visual acuity.
* Usable across large-screen and small-screen devices, mouse and touch-screen.
* Organized as a hierarchy of pages with multiple branches.
* User to be able to click on links or buttons to follow one of N selected paths downward in a hierarchy until the desired item is found. (And upward via a “previous page” button or similar mechanism.)

The site content is almost exclusively static (primarily PDF documents), with periodic additions or substitutions (e.g. an updated document). Deletions are possible, but probably infrequent.

Experimentation has shown that the Post mechanism isn’t what I need (wasn’t obvious in the beginning). Instead, Pages appear to be the desired approach. I’ve been able to create multiple pages and put them in a hierarchy, confirmed by indenture in All Pages. The Insert/Edit Link mechanism using “…or link to existing content” allows me to insert what appears to be a link in the text on the page, but that link cannot be used to get to the “linked” page, it’s just text.

I’ve looked for answers in the tutorials and in the Codex, read quite a number of exchanges in the Forum, but haven’t found an answer. Probably it’s because I don’t know the proper terminology or how to phrase the question.

I’m hoping you can help or refer me to information I haven’t found yet. Seems to me this should be simple, but it doesn’t feel that way!