SP access settings?

I have a SP site with a user group set up in read only mode at the top level.  I recently created a new page within that site but my user group does not have access to it.  When I view Group Permissions, there are multiple pages where they have "limited access"

Why do they have limited access when they should have access to it from the top level?  When I created that new page, why did it not give them access?

Any articles or anything that can walk me through the permissions for SP you would recommend?