[throwaway2016a]

The parent question was about static site hosting so one would likely use a static site generator like Jekyll.

If you want a CMS you need to either install it on a server (via Amazon EC2) or use a serverless product like AWS Lambda (which lets you run functions on demand.

But with a static site generator you will usually run and test your site locally before it generates static .html files and pushes to S3. But S3 just hosts static content. The only thing it can do that approaches anything dynamic are redirects. You can also lock down permissions by role but you wouldn't want to do that for a public static site.