It makes sense, even in 2020 that this process of labeling is how you create a Search Engine Results Page out of pages Pagerank 2020 identifies, identify spam, identify monetisation trends and promote content first pages and user friendly content above others. You can also imagine that over time, Google should get a lot better at working out quality SERPs for its users, as it identifies more and more NEGATIVE ranking signals, thereby floating higher quality pages to the top as a second order effect. A end-result of this could be that Google gets an amazing SERP for its users.
QUOTE: “And we do that across the whole website to kind of figure out where we see the quality of this website. And that’s something that could definitely be affecting your website overall in the search results. So if you really work to make sure that these comments are really high quality content, that they bring value, engagement into your pages, then that’s fantastic. That’s something that I think you should definitely make it so that search engines can pick that up on.” John Mueller, Google 2016
A navigational page is a simple page on your site that displays the structure of your website, and usually consists of a hierarchical listing of the pages on your site. Visitors may visit this page if they are having problems finding pages on your site. While search engines will also visit this page, getting good crawl coverage of the pages on your site, it's mainly aimed at human visitors.
I think ranking in organic listings is a lot about trusted links making trusted pages rank, making trusted links making trusted pages rank ad nauseam for various keywords. Some pages can pass trust to another site; some pages cannot. Some links can. Some cannot. Some links are trusted enough to pass ranking signals to another page. Some are not. YOU NEED LINKS FROM TRUSTED PAGES IF YOU WANT TO RANK AND AVOID PENALTIES & FILTERS.
Ask for a technical and search audit for your site to learn what they think needs to be done, why, and what the expected outcome should be. You'll probably have to pay for this. You will probably have to give them read-only access to your site on Search Console. (At this stage, don't grant them write access.) Your prospective SEO should be able to give you realistic estimates of improvement, and an estimate of the work involved. If they guarantee you that their changes will give you first place in search results, find someone else.