INSERT mvc OOP

<?php
//index.php
        if(isset($_POST['submit'])){
            
            $firstname = $_POST['firstname'];
            $lastname  = $_POST['lastname'];
            $email     = $_POST['email'];
            
            $obj = new Control(); // assign the object for controller class
            $obj->insert($firstname,$lastname,$email); // Pass the data in insert function
            //header("location: classes/control.class.php");
            echo "<script>alert('Inserted')</script>";
            echo "<script>window.open('index.php','_self')</script>";
        }

    ?>

    <?php
    //control.class.php
    class Control extends Model {

        public function insert($firstname,$lastname,$email) {

                $obj = new model();
                $obj->createUser($firstname,$lastname,$email);
        }

    }
    ?>
<?php
//model.class.php
    class Model extends Dbh{
        protected function createUser($firstname,$lastname,$email) {

            $sql = 'INSERT INTO users (firstname,lastname,email) VALUES (?,?,?)';
            $stmt = $this->connect()->prepare($sql);
            $stmt->execute([$firstname,$lastname,$email]);
        }
    }