scripts not loading

You should enqueue scripts in functions.php itself with wp_enqueue_scripts hook. Like this.

function my_jsfile() {

  wp_register_script( 'menu', get_template_directory_uri() . '/js/menu-effect.js', array() );
  wp_register_script( 'thumbnail', get_template_directory_uri() . '/js/thumbnail-effect.js', array() );

  wp_enqueue_script( 'menu' );
  wp_enqueue_script( 'thumbnail' );

}
add_action( 'wp_enqueue_scripts', 'my_jsfile' );

And also you should remove wp_enqueue_script from header.php as well as script links.

And finally make sure your script paths are correct.

tech