Wordpress based ajax form submission not working - php

Question

Basically I am beginner to WordPress and ajax and I am trying to make a custom newsletter with Wordpress using ajax method. It seems something is wrong with my code which I have been trying to sort for quite while. any help would be appreciated.
front page code:
<form id="myform" method="POST">
<div class="newsletter" data-aos="fade-up" data-aos-delay="300">
<h2>Newsletter</h2>
<div class="form-element">
<input type="text" class="input-element" name="email" id="email" placeholder="Email"><br>
<span class="email-message" id="email_msg"></span>
<button class="btn form-btn" name="submit" value='Submit' id="submit" type="button">Subscribe</button>
</div>
</div>
<div class="messageDiv"></div>
</form>
ajax:
<script>
jQuery(function() {
jQuery('#myform').submit(function(event){
event.preventDefault();
jQuery.ajax({
dataType : "json",
type : "post",
data : jQuery('#myform').serialize(),
url : my_ajax_object.ajax_url,
success:function(data)
{
jQuery('.messageDiv').html(data.message);
}
});
});
});
</script>
function.php:
function my_enqueue() {
wp_localize_script( 'ajax-script', 'my_ajax_object', array( 'ajax_url' => admin_url( 'admin-ajax.php' ) ) );
}
add_action( 'wp_enqueue_scripts', 'my_enqueue' );
if(isset($_POST['email'])){
global $wpdb;
$email = $_POST['email'];
$con = new mysqli("localhost", "root", "", "blogger", 3306);
$table_name ='newletter';
$sql=$wpdb->insert("newletter", array("email" =>$email));
if($rowResult == 1){
echo json_encode(array('message' => '<h1>form submit sucesss</h1>', 'status'=> 1 ));
}else{
echo json_encode(array('message' => '<h1>error submission</h1>', 'status'=> 0 ));
}
die;
}