htaccess / wpconfig for numerous wordpress and woocommerce sites?

I want to run several wordpress and woocommerce sites with one hosting package (hostinger premium package),
each website will be installed in a seperate subfolders.

For example:
My website ‘first.com’ will be installed in a subfolder named ‘/first’
My website ‘second.com’ will be installed in a subfolder named ‘/second’
etcetera

As these sites are all different (using different themes/childthemes/plugins)I won’t use multisite.

Currently I have this in my .htaccess file:

RewriteEngine On

RewriteCond %{HTTP_HOST} ^first\.com$ [NC]
RewriteRule ^(.*)$ https://www.first.com/$1 [R=301,L] 

RewriteCond %{HTTP_HOST} ^(www.)?first.com$
# voor https: 
# RewriteCond %{HTTPS} !on
# RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}
RewriteRule ^(/)?$ first [L]

This does redirect visitors of ‘first.com’ to the wordpress site in subfolder ‘first’
However I want the url to be ‘first.com’ when they type in ‘first.com’ in their browser, but they end up in: ‘first.com/first’

What am I doing wrong? How should my .htaccess look like for multiple sites and https sites? Do I need to alter my wp-config as well ? How about the permalinks ?

I’ve searched for hours on how to setup .htaccess files for numerous wordpress/woocommerce sites.. but I can’t figure this out on my own ??