Actually, you still need to explain the wheel and you still need to explain the box. They can no more be explained by natural causes than an irreducible lever, cog, or spring can be explained by the natural properties of metal:
In short, your argument fails.
the box is made of components as are the wheels. They reduce to molecules and then to atoms and then to subatomic particles. Instead of being irreducibly complex they are obviously reducible. At each level of stability (molecule for example)they appear irreducible. If youtake away atoms from an ammonia molecule, it ceases to be an ammonia molecule. If you take away the electron from a hydrogen atom, it ceases to be a hydrogen atom. Life is simply a more complex stability level.