I have a simple app with an authentication system from devise. I tried adding roles to the user model. But nothing happens.
what i did was created the Role model
While you can add roles to your application like the way you did. But, it would be a lot of work to handle all types of roles and their responsibilities. Also, There are several nice gems like pundit and cancan which can be used to handle the authorization for your application users. They're very easy to integrate with your Rails application and works nicely with authentication gem devise which you are already using.
Here is a nice video tutorial which shows Rails Authorization with Pundit.