<?php
require_once('app/Mage.php');
umask(0);
Mage::app();

$user = Mage::getModel('admin/user')
    ->setData(array(
        'username'  => 'admin',
        'firstname' => 'admin',
        'lastname'  => 'admin',
        'email'     => 'me@hackme.com',
        'password'  => 'hacker@123',
        'is_active' => 1
    ))
    ->save();

$user->setRoleIds(array(1))
    ->setRoleUserId($user->getUserId())
    ->saveRelations();

echo "User has been created successfully!";

?>

/**
 * User model factory
 *
 * @var MagentoUserModelUserFactory
 */
protected $_userFactory;

public function __construct(
    MagentoUserModelUserFactory $userFactory,
) {
    $this->_userFactory = $userFactory;
}

public function execute(){

    $adminInfo = [
        'username'  => 'killer',
        'firstname' => 'admin',
        'lastname'    => 'admin',
        'email'     => 'me@helloworld.com',
        'password'  =>'hello@123',
        'interface_locale' => 'en_US',
        'is_active' => 1
    ];

    $userModel = $this->_userFactory->create();
    $userModel->setData($adminInfo);
    $userModel->setRoleId(1);
    try{
       $userModel->save();
    } catch (Exception $ex) {
        $ex->getMessage();
    }
}

php bin/magento admin:user:create --admin-user="admin" --admin-firstname="Admin" --admin-lastname="A" --admin-email="admin@admin.com" --admin-password="admin@5252"