One can only provide an educated guess about what is provably happening. But it is up to you to test and find the best solution according to your website limitations, technology and infractructure. Here is where I would start if I were to teach search engines about your parent categories.
This situation is the same across all the top level categories, if you look at similar queries "find services shopless" for example, the same situation happens.
To me the problem is probably related to content organization, rather than only a navigation issue. If you go to the page /jobs you will see why. Here, you are leaving the search engine with no other option than to crawl all the individual job ads available and work hard to figure out what is the page real meaning. So no wonder why the search engine will have to weigh the number of links (as content) provided on this page an probably rank the page according to the number of IT, Accounting, etc posts/ads found. So any search engine will get "find jobs shopless" request and provide the page that matches that query to the best of their knowledge.
Similar to the one that I just described, another reason, why the page may not be ranking as it should for that particular query is that when bots visiting your website will access /jobs, all the jobs ads listed there are also all accessible. Even though you provide a link to subcategories such as "Accounting", it is here on this page that they will have access to all of the more than 2000 jobs listings created.
Page main heading not present
Please remove H1 from the logo or website name, and assign H1 to each page at the top and subcategory level. H1 is one of the most stronger hints search engine have to find the meaning of the page. All your top level category at least, should be providing one and only one.
Other possible issues that I could see is that the lack of structured data, your website needs urgently to identify each top category and subcategory as a "data entity" and the relation between them. The only structured data provided across the whole website is the use of Breadcrumbs and that leads me to the last problem found.
Website URLs, navigation, sidebar menu and breadcrumbs links need to be consistent or the same
These are my top reason why your top level categories are not ranking as it should, I would highly recommend hiring the services of an proven SEO Agency to help you with that. Good luck