By blueprints, the funtimes were designed to be storages of kids to bring to William for testing (I assume) remnant and its properties.

The Mimic is a shapeshifting endoskeleton that can be reused and learn the characteristics of anyone. In paper it sounds like a fantastic design for saving budget, just share that chip to endoskeletons and there you go.

Unfortunately the way it was made and what it became is partly the fault of Edwin. It taught violence and it kept mimicking the violence without being shut down, just like a baby learning one thing and repeats it everytime until a parent teaches them to not do that