This app is based on the React Context API demo from Wes Bos which is described in the video at https://www.youtube.com/watch?v=XLJN4JfniH4 and in GitHub at https://github.com/wesbos/React-Context.
This version uses redux-easy (https://www.npmjs.com/package/redux-easy) instead of the Context API. Even though it uses Redux, I think the redux-easy approach is simpler than the Context API.
In particular, check out the code in src/index.js and src/App.js.
This was created using create-react-app. It contains some files that it generated that aren't really needed.