Inspired by how NeXTSTEP bundles work.

People keep missing Java's ideas due to OpenSTEP collaboration before Java came to be.

https://cs.gmu.edu/~sean/stuff/java-objc.html

https://en.wikipedia.org/wiki/Distributed_Objects_Everywhere

JAR has additional structure to it, though it's mostly optional stuff, like metadata and code signing:

https://docs.oracle.com/en/java/javase/21/docs/specs/jar/jar...

Wait until you learn what an iOS app's .ipa file is.