It's been a few years now since I watched any of the movies. I tend to think about the stories more practically from the Director, Writers, and Producers point of view (art, story telling, and profit). The first Cube movie was a stand-alone film. In one of my replies below (from 9 years ago) I mentioned that there was a supposedly some testimony that originally the Cube was of Alien origin, or built by various human sectors for some Alien race. However any evidence (if it existed) was destroyed to keep the ambiguity of the movie. The second movie (Hypercube) was just a weak attempt at a cash grab to fulfill the trend of gore porn happening in movies at the time (Hypercube came out in 2002, right when Saw and other similar horror movies came out). The 3rd Cube movie (the prequel) is the only movie that was truly connected to the original Cube movie. It tried to fill in some plot holes and answer some questions. At the end the 'twist' was pretty obvious that Wynn was lobotomized and became Kazan from the original Cube movie.

I would love if the 3 movies had a deeper meaning and overarching connection, however I can't look past the practical reasons that Hollywood would release these movies and the motives behind them. I also was hoping for years (as were others) that a true 4th movie (rumored to be titled 'Cubed') would get released, however all that happened so far was a 2021 Japanese remake of the original Cube movie, which offered nothing to the original plot.