ANDF had already done (or at least tried to do) the "write once, run anywhere" thing. The JVM followed in the footsteps of similar longstanding efforts at UCSD, IBM and elsewhere. There was some innovation, but "world's most advanced virtual machine" took thousands of people (many of them not at Sun) decades to achieve. Sun's contribution was primarily in popularizing these ideas. Technically, it was just one more step on an established path.
Sure plenty of the ideas in Java were invented before, standing on the shoulders of giants and all that. The JIT came from Self, the Object system from Smalltalk, but Java was the first implementation that put all those together into a coherent platform.
