Simple Mod Rewrite Question (site.com/string to site.com/?string)

Hello.

I am trying to figure out how do I make my server show pages in this format:

When server side those will be translated correspondingly to:

Also if a user enters the second option in the browser (site.com/?page1), he should be redirected to the main URL at site.com/page1.

Currently I use this:

RewriteEngine on
RewriteRule ^([A-Za-Z0-9]+)$ /?$1

Code (markup):

But I keep getting a 500 Internal Server Error.

 

You are probably getting the HTTP 500 error due to A-Za-Z. That can be rewritten as A-Za-z or simply A-z, but it still won't detect the . in .html

Instead try:

RewriteRule ^([^/]+)$ /?$1 [L]

Code (markup):

 

I still get a 500 error with this in my htaccess:

The error appears in both cases:
site.com/?page or site.com/page