Where the ideas come from
Every idea is something Google itself shows for your search. People also ask is the box of questions Google adds to many results pages. Related searches are the searches it suggests at the bottom. Both change with the place and the day, so the same topic can give a different list next month.
The five pages Google shows now tell you what kind of page to write. If they are service pages, write a service page. If they are guides, write a guide. That is search intent, and it matters more than any single keyword.
Why there are no search volumes
Monthly search numbers come from paid data sources, and the free ones are guesses. A question that Google shows on its own results page is already proof that people ask it.