profile/
It is necessary that when going to profile/{nickname} used profile.php template, and not notFound() 404. How can I do?
and why static page can't have children?)
Sorry for my bad english

If you have a page "Profile" the permalink will be yourdomain.com/profile.
Normal pages can have subpages or children, static pages not.and why static page can't have children?)
how it should look
But then, these pages will be displayed on the main page as news, but I don’t need it because I want to use them as static
Custom template for the pages
No, you can set one page as mainpage in the field "Homepage" at "Settings" > "General" > "Advanced".But then, these pages will be displayed on the main page as news, but I don’t need it because I want to use them as static