well yes and no. you could use url vars, but not with a include. What you need to do is have a second var that has your "target content" for instance
page.php?info=index
you cant use that in a include, how ever you could do this
$info = "index"
then include your page. now also you could make a header navbar and footer page, then when someone clicks it takes them to the new page just like a non php link would do, then you include in your header, navbar and footer, around your content. Clear as mud??? 😉