[Custom-Theme] WordPress Custom Contact Form

So for my Custom Theme I’ve created a Custom Contact form and I have error messages but the thing is the error messages are showing even though it’s the person first time on the page. Basically I only want the error message to show when the user has clicked submit and they have missed something.

Code:

<?php
	//Response Generation Function
	$response = "";

	//Function to Generate Response
	function my_contact_form_generate_response($type, $message) {

		global $response;
	}

	//Response Messages
	$not_human       = "Human verification incorrect.";
	$missing_content = "Please supply all information.";
	$email_invalid   = "Email Address Invalid.";
	$message_unsent  = "Message was not sent. Try Again.";
	$message_sent    = "Thanks! Your message has been sent.";

	//User Posted Variables
	$name = $_POST['message_name'];
	$email = $_POST['message_email'];
	$message = $_POST['message_text'];
	$human = $_POST['message_human'];

	//PHP Mailer Variables
	$to = get_option('admin_email');
	$subject = "Someone sent a message from ".get_bloginfo('name');
	$headers = 'From: '. $email . "\r\n" .
	'Reply-To: ' . $email . "\r\n";

	if(!$human == 0){
	if($human != 2) my_contact_form_generate_response("error", $not_human); //not human!
	else {

	  //validate email
	  if(!filter_var($email, FILTER_VALIDATE_EMAIL))
	    my_contact_form_generate_response("error", $email_invalid);
	  else //email is valid
	  {
	    //validate presence of name and message
	    if(empty($name) || empty($message)){
	      my_contact_form_generate_response("error", $missing_content);
	    }
	    else //ready to go!
	    {
	      $sent = wp_mail($to, $subject, strip_tags($message), $headers);
	      if($sent) my_contact_form_generate_response("success", $message_sent); //message sent!
	      else my_contact_form_generate_response("error", $message_unsent); //message wasn't sent
	    }
	  }
	}
	}
	else if ($_POST['submitted']) my_contact_form_generate_response("error", $missing_content);
?>

<?php get_header(); ?>
<!-- Page Header -->
<section class="page-title">
	<h1>
	<?php wp_title(''); ?>
	<div class="light-separator small center"></div>
	</h1>
</section>
<section class="contact-page custom-container">
	<h2>Get in touch!</h2>
	<div class="dark-separator small center"></div>
	<div id="respond">
		<?php echo $response; ?>
		<form action="<?php the_permalink(); ?>" method="post">
			<div class="contact-form col-md-12">
				<div class="col-md-6">
					<br><input type="text" name="message_name" class="form-name" value="<?php echo esc_attr($_POST['message_name']); ?>" placeholder=" Name *">
					<small class="error"><?php echo ($_POST["message_name"] == "") ? "Please fill in the required field" : ""; ?></small>
				</div>
				<div class="col-md-6">
					<br><input type="text" class="form-email" name="message_email" value="<?php echo esc_attr($_POST['message_email']); ?>" placeholder=" E-Mail *">
					<small class="error"><?php echo ($_POST["message_email"] == "") ? "Please fill in the required field" : ""; ?></small>
				</div>
				<div class="col-md-6">
					<br><input type="text" class="form-tele" name="message_tele" value="<?php echo esc_attr($_POST['message_tele']); ?>" placeholder=" Telephone *">
					<small class="error"><?php echo ($_POST["message_tele"] == "") ? "Please fill in the required field" : ""; ?></small>
				</div>
				<div class="col-md-6">
					<br><input type="text" class="form-subject" name="message_subject" value="<?php echo esc_attr($_POST['message_subject']); ?>" placeholder=" Subject *">
					<small class="error"><?php echo ($_POST["message_subject"] == "") ? "Please fill in the required field" : ""; ?></small>
				</div>
				<div class="col-md-12 col-sm-12 col-xs-12">
					<br><textarea type="text" class="form-message" name="message_text" placeholder=" Message *"><?php echo esc_textarea($_POST['message_text']); ?></textarea>
					<small class="error"><?php echo ($_POST["message_text"] == "") ? "Please fill in the required field" : ""; ?></small>
				</div>
				<div class="submit-btn col-md-12">
					<input type="hidden" name="submitted" value="1">
					<input type="submit" class="form-button" value="Send">
				</div>
				<div class="all-errors">
					<small class="error"><?php echo ($_POST["missing_content"] == "") ? "Validation errors occurred. Please confirm the fields and submit it again." : ""; ?></small>
				</div>
			</div>
		</form>
	</div>
</section>
<?php get_footer(); ?>

I’ve been copying this tutorial to make a Custom Contact form for WordPress

Tutorial