Website can not be fetched (by Google and others)

So.. I don't really know what goes wrong here. Therefore, it's probably bit of a vague question.

I wanted to improve my website's SEO. The final improvement that I want to realize are better URL's. (To my Surprise) it worked quite well! But while using Google's Search Console, Google (and others like: httpstatus.io) say that they can't fetch any of the pages affected by these new lines of codes. I guess it has something to do with the http status code... That's what I don't understand. Why?

I want to redirect requests like this:

http://ift.tt/2blDMlW -> http://ift.tt/2bjeM1K

(While the URL does not change of course.)

This is only required in the main directory.

So I started to Google the problem and used my own (very basic) knowledge, and this is de code I placed in the .htaccess file:

RewriteEngine On

RewriteCond %{HTTP_HOST} ^XXX\.XXX\.XXX\.XXX
RewriteRule (.*) http://ift.tt/1tdRfEE [R=301,L]

RewriteCond %{HTTP_HOST} !^www.example.net$ [NC]
RewriteRule ^(.*)$ http://ift.tt/1tdRfEE [L,R=301]

RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{SERVER_NAME}/$1 [R,L]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^/]*)(?!/.*)$ /index.php [L]

This is what I added to the index.php file:

<?php 
    function get_requested_page(){
        $requested_uri = $_SERVER['REQUEST_URI'];
        $requested_page = $requested_uri;
        $requested_page = explode("/", $requested_page);
        return($requested_page);
    }

    $requested_path_array = get_requested_page();

    $i = 0;
    foreach($requested_path_array as $part){
        if($i !== 0){
            $path .= "/" . $part;
        }
        $i++;
    }

    if (strpos($path, '?') !== false) {
        $PathParameters = substr($path, strpos($path, "?"));
        $arr = explode("?", $path, 2);
        $path = $arr[0];
    } 

    $path .= ".php";

    if($path == "/.php"){
        $path = "/home.php";
    }

    $filePath = $_SERVER['DOCUMENT_ROOT'] . $path;
    $ErrorFilePath = $_SERVER['DOCUMENT_ROOT'] . "/404.shtml";

    if(file_exists($filePath)){
        header("HTTP/1.1 200 OK");
        require $filePath;
    } else {
        //echo("https://$_SERVER[HTTP_HOST]" . $path);
        //echo("<h1>404 ERROR - Page not found</h1>");
        //die("<p>This page does not exist (anymore), or is moved.</p>");    
        header('HTTP/1.0 404 Not Found');
        include $ErrorFilePath;
    }

?>

Thnx for looking in to this. And sorry if I made some bad mistakes in my code and/or in this post. English is not my native language :)