This article was my first exposure to React, and it goes through the basics of building a very simple "list of people" using nothing more than a single HTML file. It doesn't even use JSX, instead showing you how to build the raw JS that the JSX would compile to. I found it to be a great introduction without a lot of overhead to learn.

http://jamesknelson.com/learn-raw-react-no-jsx-flux-es6-webp...