This is intentional, as an empty homepage is not a typical user scenario. You can hide the categories label via custom CSS, or custom JS if you want to hide it only when there are no categories.
Where are the users I did not approve
I set Admin Approval in Registration option in my website, and sometimes I see spam users register and I click on Red Cross button in Registration Queue.
Now I wanted to see all of them, but I see only the ones I approved manually. I did not see any options to see them.
I also searched one of them, but it found nothing.
Would you help me how may I see them?
Thanks in advance
You can't. User accounts aren't created until approved.
So you mean another user can register with one of those users again? Am I right?
That's right, the username/email can be used by another person if you reject someone.