Given that you rank for the content that you have on your site, content is definitely the king of SEO. I've seen cases of people who have the wrong kind of content on their sites and end up ranking for the wrong keywords!

No one king in SEO. SEO is ongoing porcess. If content are king then why we are needful to refresh it after some time. There is always need to update the content and make best strategy without right strategy content are useless bullet. So always update all the sections in SEO if anyone want to stay at top for long time.

Ok but where should you put that content?
do you mean on a blog or something?

Content forever is king

Yes, content plays an crucial role. Each and every text form helps makes easy for serach engines.