If you created a 'plain user' account, it means that you created an account with the user Role.
If the user you created and added to the user Role does not have access based on the Role permissions then they simply will not have access.
Use Manager > Access Controls > Roles > User to view and set the permissions available to the User Role.
Beyond Roles, for systems that have been around for a while with a number of users creating things, you will find that permissions for those things are troubling if you suddenly decide to restrict permissions. Every search, every dashboard, every lookup and others have permissions assigned at the role level if they are elevated from Private.
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