Then you don’t understand von Neumann’s universal constructor model. A simple search on Wikipedia shows that von Neumann’s universal constructor model is the same as common ancestry, just applied to mechanical rather than biological systems. The “universal constructor” isn’t a reference to some ‘universal common designer,’ it’s von Neumann’s name for the mechanical ‘universal common ancestor’ which self-replicates. So the fact that von Neumann’s model shows the same nested hierarchy pattern as biological lifeforms doesn’t help your case, it hurts it.