autoloading error 질문입니다.

고생하십니다. 새해 복 많이 받으세요 선생님. 

코드는 다음과 같습니다.

<?php

/**
 * Classes Autoloading (PSR-4)
 */

// include './Classes/MyClass.php';

use Classes\MyClass;


spl_autoload_register(function ($classname) {
  include $classname . '.php';
});

new MyClass();

디렉토리 구조는 

/Users/chamusong/Desktop/php-oop/functions/SPL/4

Classes-MyClass.php         index.php

이렇게 되어있습니다.

오류내용은 다음과 같습니다.

PHP Warning:  include(Classes\MyClass.php): failed to open stream: No such file or directory in /Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php on line 13
PHP Stack trace:
PHP   1. {main}() /Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php:0
PHP   2. spl_autoload_call($class_name = 'Classes\\MyClass') /Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php:16
PHP   3. {closure:/Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php:12-14}($classname = 'Classes\\MyClass') /Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php:16
PHP Warning:  include(): Failed opening 'Classes\MyClass.php' for inclusion (include_path='.:/opt/homebrew/Cellar/php@7.4/7.4.27/share/php@7.4/pear') in /Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php on line 13
PHP Stack trace:
PHP   1. {main}() /Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php:0
PHP   2. spl_autoload_call($class_name = 'Classes\\MyClass') /Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php:16
PHP   3. {closure:/Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php:12-14}($classname = 'Classes\\MyClass') /Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php:16
PHP Fatal error:  Uncaught Error: Class 'Classes\MyClass' not found in /Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php:16
Stack trace:
#0 {main}
  thrown in /Users/chamusong/Desktop/php-oop/functions/SPL/4/index.php on line 16

오류내용을 보면 경로의 문제인 것 같기도 합니다. 

namespace Classes;

class MyClass 
{
}

use Classes\MyClass;

spl_autoload_register(function ($classname) {
    include $classname . '.php';
});

new MyClass();

<?php

/**
 * Classes Autoloading (PSR-4)
 */

// include './Classes/MyClass.php';

use \Classes\MyClass;


/* spl_autoload_register(function ($classname) {
  var_dump($classname);
  include $classname . '.php';
}); */
spl_autoload_register(function ($classname) {
  include './' . str_replace('\\', '/', $classname . '.php');
});

$myc = new MyClass();
$myc->foo();