FWIW, even with the "simple explanation," I'll echo OP's statement that the README doesn't really explain what it is or what it's solving. "Generates new versions of the structures" might mean something really clear to you, but even the phrase "data modeling" is enough to trigger lots of conflicting baggage in my head. Also: it took awhile it realize it's for Scala. I initially assumed this was a Smithy-like competitor.

It looks neat (once I found your docs)! Show what it is and what it solves in your README! The structural inheritance is slick.