display user list on homepage

That is the correct code, but SUL currently only permits the shortcode to appear on pages. I have to re-think whether that is a good idea or not. While you are the first person to ask about displaying the list elsewhere, I don’t see a lot of reason for having this limitation.

// Return only if we're inside a page. This won't list anything on a post or archive page.
if ( is_page() ) {
  do_action( 'simple_user_listing_before_shortcode', $post, $query_id );
  return $output;
  do_action( 'simple_user_listing_after_shortcode', $post, $query_id );
}