prevent default not stopping page refresh. Passing form information to and from php with ajax in a wordpress site

I have seen a number of methods dating back to about 2011 in order to take a form and have its data posted via ajax.jquery. I have tried a couple and am just getting the page to reload despite using preventdefault functions.

I am trying to take data from my form, have the jQuery listen for the form submit by targeting the actual form id and then call a PHP function in order to have that data posted to the db. Ultimately nothing happens other than a page reload. Since this is a WP page, I know that some of the functions and handling differ from regular webpages. Things like the ajax url, can be passed back to the functions etc. That is why I Am posting this here.

the form:

function add_entry(){
    ?>
    <form action="" method="post" id="ajax-add-to-form" autocomplete="off">
        <input type="text" id="FName" name="FName" placeholder="First Name" value="" required>
        <input type="text" id="LName" name="LName" placeholder="Last Name" value="" required>
        <select id="size" required>
            <option value="">Size</option>
            <?php  for($i=1; $i<=15; $i++){?>
                <option value="<?php echo $i; ?>"><?php echo $i; ?></option>
            <?php } ?>
        </select>
        <input type="text" id="MobileNumber" name="MobileNumber" placeholder="Phone Number" value="" required>
        <input type="email" id="Customer_Email" name="Customer_Email" placeholder="Email Address" value="" required>
        <input type="submit"  name="ajax-add-to-form" value="Add to">
<?php
    
    }
add_shortcode('add_entry', 'add_entry');


</form>

the jquery

jQuery('document').ready( function(){
jQuery('#ajax-add-to-form').on('submit', function(e){
e.preventDefault(); 
jQuery('#jx-loading').show();
jQuery.ajax({
    type: 'post',
    url: my_ajax.ajax_url,
    data: { 
    action: 'ajax-php-function'},
    success: function(data)
    {jQuery('#jx-loading').hide();}
})          
}); 
return false;       
});

the php

function ajax-php-function() {          
    global $wpdb;   
    $table = "mytablename";     
    $FName= $_POST['FName'];    
    $LName= $_POST['LName'];    
    $MobileNumber= $_POST['MobileNumber'];  
    $Email = $_POST['Email '];          
    $data = array(
    'FName' => $FName,
    'LName' => $LName,      
    'MobileNumber' => $MobileNumber,        
    'Email' => $Email);     
    $success = $wpdb->insert( $table, $data );          
    if($success)
    {echo json_encode($last_data);} 
    else{       echo 'error';   }   die;            
}