Hi Donovan
Ignore any role types you have set up. You should not have system wide roles at all and you are correct; forget about groupings on the front page. Your users should just have the default role of authenticated user.
Before they log in (if your front page has the list of courses)they should all see the courses available. Then they choose the course they want to enrol in and enrol with the key you will have given them.
After that once they have logged in they will only have their own courses that they are enrolled in.
I am happy to have a look if you want to give me a log in but I don't think you have a problem here; just a need to understand the way moodle displays courses to those who are logged in and then those who have enrolled in various courses or not. Certainly there is no need to edit any roles.