How do I make a different page my home page?

Any CMS page can become the home page:

1. Go to Content → All Pages and click the edit (pencil) icon on the page you want.
2. Tick Set as homepage.
3. Click Save changes.

The page then opens at your store's main address, and the list marks it with a home tag. Your previous home page keeps its content and gets a new address such as home-1, so nothing is lost.

You can't untick the box on the current home page. To change it, tag another page as home instead. General Pages don't have this option.