301 Redirect for .html pages - regex

Question

After searching StackOverflow and trying multiple Regex approaches, I can't seem to get a redirect that will make every example.com/example.html page on a site instead point to simply example.com/example. My .htaccess file looks like this:
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
My first attempt was
RedirectMatch 301 (.*)\.html$ https://example.com$1
But while it worked for the individual .html pages, it resulted in the home page redirecting to https://example.com/index and that is a 404.
My latest attempt was to add this at the bottom
RewriteRule ^(.*)\.html$ /$1 [L,R=301]
That didn't work at all. Then I put that same line BEFORE the line
RewriteRule . /index.php [L]
So the block looks like this
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)\.html$ /$1 [L,R=301]
RewriteRule . /index.php [L]
But that just resulted in the site loading really slowly and when it loaded the images and stylesheets were broken.
Is there a way to do this that I'm just not understanding?

Answer 1

You may use this redirect rule before your existing rule:
RewriteEngine On
# removes .htm, .html, index.htm or index.html - case ignore
RewriteCond %{REQUEST_URI} ^/(.*/)?(?:index|([^/]+))\.html?$ [NC]
RewriteRule ^ /%1%2 [R=301,L,NE]
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . index.php [L]