get post id from wp_insert_post for get_template_part

Declare $my_post_id as global in your code. Declare $my_post_id as global in the-post.php template. Your code:

global $my_post_id;
$my_post = array(
    'post_type'  => 'theposttt',
    'post_title'    => 'test',
    'post_content'  => '',
    'post_status'   => 'publish',
    'post_author'   => 1
);
$my_post_id = wp_insert_post($my_post);
if(is_wp_error($my_post_id))
    $my_post_id = 0;

Now, you can use $my_post_id in the-post.php template. Possible values: 0 ( failure ), post id ( success ).