The Amazon S3 plugin is about the service S3 storage in Amazon.
It is divided in two parts, one is working with the media library and the other one is working with downloadable WooCommerce products.
This plugin can work without WooCommerce too.
The point of the media library is to copy all your images to the S3 storage. So then your server is not going to serve them, they are going to be served by S3, therefore the server is going to be faster.
You can copy any type of file to S3 from the media library, it doens’t have to be only images!