With your explanation and after your comment, this should fix your issues:
RewriteEngine On
# Redirect Trailing Slashes...
RewriteRule ^/?(.+)/$ /$1 [R=301,L]
# Handle Front Controller...
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^.*$ /index.php [L]