I think you might be misunderstanding how this service works.
The Github repositories don't serve the packages.
Jitpack checkouts the repository code, builds it, and serves it like a normal maven repository. Here is a sample repository https://github.com/jitpack/maven-simple and the maven repository it is served from: https://jitpack.io/com/github/jitpack/maven-simple/0.1/maven...