Successful ajax call returns lots of whitespace and text of code with 0

Question

I am trying to convert a javascript variable to a PHP variable with ajax. On paper, ajax tells me there aren't any errors, but php doesn't recognize the REQUEST['name_here'], and every time I try to console.log the data, it prints lines of whitespace, and a big chunk of my code as text, along with a 0. Has anyone ever come accross an issue like this before?

// ajax action
add_action( 'wp_ajax_Print_Roster123_function', 'Print_Roster123_function' );

code here:

<script src="https://code.jquery.com/jquery-3.6.4.js" integrity="sha256-a9jBBRygX1Bh5lt8GZjXDzyOB+bWve9EiO7tROUtj/E=" crossorigin="anonymous"></script>
<?php

function Print_Roster123_function() {
    global $wpdb;
  ?>
  
 <script>
 

        jQuery(document).ready(function($) {
           $("#Change1").change(function() {
               // This toggles the select tag
        var Class_Initial = $(this).find("option:selected").text();
        
        
        $.ajax({
           url: ajaxurl,
           // action is the name of the function in final_cart
           data: { 
                 'Class_Initial' : Class_Initial,
                'action' : 'Print_Roster123_function'

           },
           success: function(data) {
               // prints out many lines of whitespace, along with all of my code and 0
               console.log(data);
           },
        error: function(errorThrown){
            console.log(errorThrown);
        }
        });

    });
});
</script>
  
  <?php
    
    if ( isset($_REQUEST) ) {
                // Php doesn't recognize 'Class_Initial'. If I try echoing out $New_Var, nothing shows up
                $New_Var = $_REQUEST['Class_Initial'];
    }
        ?>