I don't know why you think "service" is a word that systemd got from Windows. The name "service" actually came from the usage of the "service" script to run ini

I don't know why you think "service" is a word that systemd got from Windows. The name "service" actually came from the usage of the "service" script to run initscripts, like "sudo service httpd start". A systemd "service" is just a declarative description of a daemon that allows systemd to start and stop it.