Registration type not registering First and Final title

I am making a customized registration type which works utilizing username and electronic mail inputs, however after I embody First and Final title fields it will not let me register.

Right here is the shape:

<type id="_wb_register" motion="<?php echo home_url(); ?>" methodology="submit">

    <p>

        <label for="_wb_register_username"><?php _e('Username:', 'wb'); ?></label>
        <enter sort="textual content" title="username" id="_wb_register_username" />

    </p>

    <p>

        <label for="_wb_register_user_first_name"><?php _e('First Title:', 'wb'); ?></label>
        <enter sort="textual content" title="user_first_name" id="_wb_register_user_first_name" worth="<?php echo esc_attr( wp_unslash( $first_name ) ); ?>" />

    </p>

    <p>

        <label for="_wb_register_user_last_name"><?php _e('Final Title:', 'wb'); ?></label>
        <enter sort="textual content" title="user_last_name" id="_wb_register_user_last_name" worth="<?php echo esc_attr( wp_unslash( $last_name ) ); ?>" />

    </p>

    <p>

        <label for="_wb_register_email"><?php _e('E-mail:', 'wb'); ?></label>
        <enter sort="electronic mail" title="electronic mail" id="_wb_register_email" />

    </p>

    <div class="padding" type="top: 5px;"></div>

    <?php do_action('wb_user_panel_registration_form_bottom'); ?>

    <p><enter sort="submit" worth="<?php _e('Signal Up', 'wb'); ?>" class="button-primary" /></p>

</type>

And right here is the perform used to create the consumer upon ending the registration type:

add_action('wp_ajax__wb_register', '_wb_register_function');
add_action('wp_ajax_nopriv__wb_register', '_wb_register_function');

perform _wb_register_function() {

    $return = array();
    $return['error'] = false;
    $return['message'] = array();

    //// VERIFIES NONCE
    $nonce = isset($_POST['nonce']) ? trim($_POST['nonce']) : '';
    if(!wp_verify_nonce($nonce, 'wb-register-nonce'))
        die('Busted!');

    //// VERIFIES CREDENTIALS
    $username = isset($_POST['username']) ? trim($_POST['username']) : '';
    $first_name = isset($_POST['user_first_name']) ? trim($_POST['user_first_name']) : '';
    $last_name = isset($_POST['user_last_name']) ? trim($_POST['user_last_name']) : '';
    $electronic mail = isset($_POST['email']) ? trim($_POST['email']) : '';

    //// MAKES SURE USER HAS FILLED USERNAME AND EMAIL
    if($electronic mail == '' || !is_email($electronic mail)) { $return['error'] = true; $return['message'] = __('Please sort in a sound electronic mail handle.', 'wb'); }
    if($last_name == '') { $return['error'] = true; $return['message'] = __('Please enter your final title.', 'wb'); }
    if($first_name == '') { $return['error'] = true; $return['message'] = __('Please enter your first title.', 'wb'); }
    if($username == '') { $return['error'] = true; $return['message'] = __('Please select an username.', 'wb'); }

    ///// IF USER HAS FILLED USER, PASS, FIRST AND LAST
    if($return['error'] == false) {

        $return_registration = _wb_process_user_registration($return, $electronic mail, $username, $first_name, $last_name);
        $return = $return_registration;

    }

    echo json_encode($return);

    exit;

}

//////////////////////////////////////////////////////////////////////
///// THIS FUNCTION PROCESSES REGISTRATIONS
//////////////////////////////////////////////////////////////////////

perform _wb_process_user_registration($return, $electronic mail, $username, $first_name, $last_name) {

        //// CHECKS IF USERNAME EXISTS
        $consumer = new WP_User('', $username);
        if(!$user->exists()) {

            //// CHECK FOR USERNAMES EMAIL
            $consumer = get_user_by('electronic mail', $electronic mail);
            if(!$consumer) {

                $password = wp_generate_password();

                //// NOW WE CAN FINALLY REGISTER THE USER
                $args = array(

                    'user_login' => esc_attr($username),
                    'first_name' => $first_name,
                    'last_name' => $last_name,
                    'user_email' => $electronic mail,
                    'user_pass' => $password,
                    'position' => 'submitter',

                );

                //// CREATES THE USER
                $consumer = wp_insert_user($args);

                if(!is_object($consumer)) {

                    //// MAKES SURE HE CAN"T SEE THE ADMIN BAR
                    update_user_meta($consumer, 'show_admin_bar_front', 'false');

                    $consumer = new WP_User($consumer);

After I submit the registration type it provides me the ‘Please enter your first title.’ error, so at the very least that a part of the perform is working. I do not perceive why the First and Final names will not be being registered when the Username and E-mail work simply tremendous. Is there one thing I am lacking?