How to make WordPress Back end Page visible to lower roles than admin?
Take a look at this link - https://developer.wordpress.org/reference/functions/add_menu_page/ - take a look at the 3rd parameter - 'capabilities', in your case you have put 'manage_options' which is administrator capability - https://codex.wordpress.org/Roles_and_Capabilities#Editor For all subscribers put 'read' But spend some time and take a look at the links
add_menu_page('My Menu', 'My Menu', 'read', 'my-menu-slug', 'my_menu_page_display');