Thank you Marcus, I think the word inherit confused me, it doesn't take much.
So effectively there are two routes available when setting up the site roles.
You can either have each user given a distinct role and when setting up the roles choose all the options (allows) that you want that role to have.
Or you can view the roles as "abilities" and then have them set up so that you have the "ability" to create courses, the "ability" to amend user details. Then when you set up the user assign multiple "abilities" to each user.