That’s because it’s a helper function for adding pages to the settings section, not the lower level API you expected:
This function is a simple wrapper for a call to
add_submenu_page(), passing the received arguments and specifyingoptions-general.phpas the$parent_slugargument. This means the new options page will be added as a sub menu to the Settings menu.https://codex.wordpress.org/Function_Reference/add_options_page
Instead, you want add_menu_page https://developer.wordpress.org/reference/functions/add_menu_page/