You can use the
test-repo backend to try out Netlify CMS without connecting to a Git repo. With this backend, you can write and publish content normally, but any changes will disappear when you reload the page. This backend powers the Netlify CMS demo site.
test-repo backend can't access your local file system, nor does it connect to a Git repo, thus you won't see any existing files while using it.
To enable this backend, add the following lines to your Netlify CMS
backend: name: test-repo