AJAX POST PHP NOT ACCEPTING?

I understand this has been asked multiple times but I am unsure why this isn't working!

<?php
if(isset($_POST['testingajax'])) {
    echo "Received";
} else {
    echo "Not received";
}
?>

<button onclick = 'sendAjax()'>click me</button>

<script>
function sendAjax() {
    $.ajax({
    type: 'POST',
    url: 'test.php',
    data: {
      testingajax: 2
    },
    success: function(data) {
      console.log("AJAX POST SENT");
    },
    error: function (jqXHR) {
      handle.innerText = 'Error: ' + jqXHR.status;
    }
  });
}
</script>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

This is what shows after clicking the button, it should say Received

I have tried changing the URL to http://localhost/TESTINGPLANNER/src/test.php and ./test.php but no luck. Also, I have changed testingajax: 2 to 'testingajax': 2.

From the network screenshot it seems like AJAX it is working so I am not sure where the issue is.