On models of personality typing
In a self-organizing system with just a few rules, natural clusters will form and cohere. These convergences move only within their own borders, though one needs to be outside the border to recognize that. These sets can be enneagram types, astrological signs, DSM diagnoses, … . There will be many likenesses and unique differences and the likenesses will enable people to fit themselves into a comfortable pattern. Most people will place in the background the parts of themselves which don't quite fit. And then the model becomes,if not Truth, a generally accepted option for understanding each other.
For the idea to hold, it isn't necessary to have any god or supernatural belief, beyond accepting self-organizing ... seeing the likeness creates the patterns and then adopting the pattern finds more likeness, reinforcing over and over, enlarging and pruning, until a typology is built and naming rights are claimed for the construct, and the typology is taught and made complex.
See, for instance, Game of Life Cellular Automata, Andrew Adamatzky, 2010 for discussions of cellular automata, boundaries, convergence, and a lot of the convergences (glider, cross, … ) and applications.