First off, you are dealing with a few things in your question. I will try and go through it for you in no particular order.
As far as sitemaps go, they have nothing to do with a pages or sites performance generally. It is just a way to tell Google what pages you have. Where sitemaps are necessary is when part of your site cannot be crawled by a search engine. The common cases for this is where it is impossible to link all of your pages effectively, your links cannot be crawled due to a JavaScript issue, your content or some of your content exists behind a paywall or login. Most of the time, Google only uses your sitemap to determine if they can crawl your site properly by auditing what they find against your sitemap. Nothing more.
You are confusing the query results within a SERP (search engine result page) with a page being indexed. These are two different things.
You can tell if a page is indexed specifically by using a site: query. Here is an example.
site:example.com/mysubject/mypage.html
If you find your page, then the page is indexed.
What you are experiencing is likely a page performance issue. When you make your star wars query, the page you see first is the page that performs for that query best. Google will only show one or two SERP links per SERP page for any site. It is possible that more than two are shown if a site is popular or if the query result set is limited or weak.
You can try:
site:example.com star wars
This should show you what pages on your site would normally be found using the star wars query.
Another thing you have to know is that the Internet is HUGE!! You are competing with a huge number of other pages and sites unless you have a very unique site topic with little or no competition. The odds of a site appearing on the first page is rather rare most of the time. Unless your sites search performance is stellar, it is very difficult to rank within the first few results. This is where investigating your competition comes into play.
There are plenty of very good SEO answers to questions on this site. You can use the SEO tag to sort through the more recent answers. Since SEO changes rapidly and knowledge changes rapidly, I recommend reading the more recent answers more than older answers. We have some real experts here. Really.
