Only first category!

by

If I understand you correctly, you want to display the parent Categories themselves, and not their posts, correct? get_terms is what you need.

$top_level_categories = get_terms( 'category', array(
    'parent' => 0, // This will get ONLY top level items
    'hide_empty' => false // This will make sure even empty categories are returned
) );
print_r( $top_level_categories );