Hello @kartik,
If you really wanted to, you could do all the work that Composer does manually, but you definitely should not. Installing Composer is easy, it's just a matter of getting the composer.phar file and running commands on it.
You do not need to run Composer on your server as well as locally, once you run composer install or composer update your project will have all its dependencies available and you can just upload it straight to your server.
Hope it helps!!
Thank You!!