My /user/index.php does not open as / user / (.htaccess problem)

I just created the file .htaccess so you do not have to name the label of the files to open them (delete the .php of contacto.php , for example).

It worked for me, but the problem is that now going to example.com/user, I try to open user.php , when what I should do is use the index.php inside (since user is a folder, inside contains index.php )

I hope you have explained me well, here is the code of .htaccess :

RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^/]+)/$ $1.php
RewriteRule ^([^/]+)/([^/]+)/$ /$1/$2.php
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !(\.[a-zA-Z0-9]{1,5}|/)$
RewriteRule (.*)$ /$1/ [R=301,L]

Edited: I also just noticed that this code would only work with .php, and I need one that works with .html

Error: The requested URL /user.php was not found on this server.