What are the chances of static web content when it comes to ranking high in search engines? Sometimes the content of a static website has to be changed in accordance with the nature of the site. Does such a chance push the site's rankings further up? Or is it better not to lay our hands on the content of a static website?
Static content is absolutely fine. There are some things that don't change all that often, and Google doesn't expect you to be changing content arbitrarily. Only change things if they need to be changed, not just for the sake of it. Static content that doesn't change for months or years has a good chance of ranking well because you have longer to build up natural links and for Google to give the page authority and credence.
There is no problem for static web content as long as the web filled original content that copyscape passed. More words more potential to get better rank at Google. e.g: 1,000+ words per page. And you do SEO off page (backlining) toward to the web. Acquire backlinks from authority sites toward the web in natural way and follow Google's update then you can rank the web to the top spot.
You could eventually improve the content by adding few words/sentences here and there using key phrases or certain keywords related to the website. Your landing page (home page) content should never be changed unless you rewrite it keeping the same key phrases in.
If your content has been the same for a long period of time, then you can make some changes in it. Add the latest updates and rewrite some part of the static content, there is no need to change the entire content.