How can the iron in the reaction of iron (ii) chloride and zinc not go to zero oxidation state?
Generally, to predict redox reactions, we consider the Standard Reduction Potentials at $25\ ^\circ\mathrm{C}$: The bigger the difference between the potentials of two redox couples, more favorable is the reaction.
$$E^0(\ce{Fe^3+ /Fe^2+})=0.77\ \mathrm{V}$$
$$E^0(\ce{Fe^3+ /Fe})=-0.04\ \mathrm{V}$$
$$E^0(\ce{Fe^2+ /Fe})=-0.44\ \mathrm{V}$$
$$E^0(\ce{Zn^2+ /Zn})=-0.76\ \mathrm{V}$$
So, when $\ce{Fe^3+}$ reacts with $\ce{Zn}$, we get $\ce{Fe^2+}$ (not $\ce{Fe}$) and $\ce{Zn^2+}$.

As for your reaction: when $\ce{Fe^2+}$ reacts with $\ce{Zn}$, we get  $\ce{Fe}$ and $\ce{Zn^2+}$.