was expecting the actual vm source code, which I believe is written in C and is an engineering marvel. This looks like just the end user install package

Interesting! Well is the sourcecode for the Java JVM not open and available?

Here's the heap implementation, for example: https://github.com/openjdk/jdk/blob/master/src/hotspot/share...

The GraalVM is a Java implementation of the Java compiler and VM and it's also on GitHub: https://github.com/oracle/graal