It's perhaps worth pointing out that 1e did not include rules for making everything in the game, such as artefacts and relics, but also many of the more powerful magical items such as the books and manuals, including the golem manuals. So there was no over-arching philosophy that everything had to have rules for making it, even when some NPC could be assumed to have made one.

The monster is semi-intelligent, which is a fair reconstruction of the movie version, I think. And the clay golem of legend went berserk too.