PHP POST receiver from jQuery Ajax

receiver.php

<?php
//Allow CORS
header('Access-Control-Allow-Origin: *');

header('Access-Control-Allow-Methods: GET, POST');

header("Access-Control-Allow-Headers: X-Requested-With");
//Allow CORS ends

echo $_GET['first_name'];

sender.js

  $(document).ready(function(){
  	var first_name = $('#firstname').val();
    var last_name = $('#lastname').val();
    var email = $('#email').val();
    var phone = $('#phone').val();
    var note = $('#note').val();

    if($('#primary_phone').is(':checked')){
        var tag = $('#primary_phone').val();
    }else{
        var tag = 'primary_email';
    }
    var data = { 
        first_name : first_name,
        last_name: last_name,
        email: email,
        phone: phone,
        note: note,
        tag: tag
    };

    $.ajax({
        method: 'GET',
        crossDomain: true,
        dataType: 'jsonp',
        crossOrigin: true,
        data: data,
        headers: {
            'Access-Control-Allow-Methods': '*',
            "Access-Control-Allow-Credentials": true,
            "Access-Control-Allow-Headers" : "Access-Control-Allow-Headers, Origin, X-Requested-With, Content-Type, Accept, Authorization",
            "Access-Control-Allow-Origin": "*",
            "Control-Allow-Origin": "*",
            "cache-control": "no-cache",
            'Content-Type': 'application/json'
        },
        url: 'https://four-seasons.storehelps.com/index.php',
        success: function(response){
            console.log("Respond was: ", response);
        },
        error: function (error) {
            console.log("There was an error: ", error);
        }
    });

  });