It's unlikely readers will come just to peruse your story locations category exclusively. I would put all in-world posts in the same blog category and then tag them with more detail.
In Wordpress, categories have evolved into an organizational level that is "above" topics. Use different categories for posts that should never be sorted together, such as one category for all in-story elements, another category for historic research that links to other websites, and possibly a 3rd category for posts about being a writer or your personal journey of writing. Posts are dated and sorted chronologically, blog-style.
For information that is not timely or does not update with on-going developments, consider using nested pages as a kind of wiki. A top Wordpress Page can be a summary or pitch for the novel, with sub-pages for individual characters and locations. Each page could be a complete profile of 1 character, with page links to their close friends and the locations they visit. Information that is not updated with multiple posts should be static. Pages always appear in the menu so they are easy to access, and a Pages menu can be styled independently of the categorical blog.
As an example, you have 2 "entries" about 2 different characters. As Posts the creation dates are important, the default is for Wordpress to try to add this date to the URL of the post. The order in which the posts were written is just as important to sorting as the category itself – all "archive" feeds in WP will always sort in a chronological order (typically reverse chronological order so newest comes first).
In contrast, Pages do not sort by date. The 2 character entries are on "equal footing", it doesn't matter which was written first, they will always appear at the same hierarchy level.
In your example you ask about sorting various in-world story elements into separate categories. You can organize your blog this way, but that will compromise you in the long run – this is assuming you've started an "author blog" not strictly a "novel blog". You may have other novels, and you'll need to decide if you want all characters from all novels to sort together, or if you want to keep this information siloed to the individual stories.
You can still allow your blog to become "self-organizing" by using 1 default category for everything, until you have a situation where a topic needs to be siloed – such as "publishing news", or in-store appearances – from your story/writing topics. Use posts as a general blog, and migrate static information into pages.