I'm not sure if this is intended as serious or tongue-in-cheek.

Obviously parents come before offspring.

The earliest form of reproduction is just binary fission - what an amoeba does by splitting itself into two. In it's simplest (origins of life) form this is just a mechanical process of a proto-metabolism (bunch of chemicals) being split into parts that are smaller versions of the "parent", e.g. some proto-cell composed of seashore froth being whipped into smaller versions of itself.

Eventually the division process became asymmetrical with the spawned child being a simpler proto-version of the adult, capable of then independently developing into the adult form. It seems life developed in the oceans before emerging onto land, so the history is probably of multi-cellular fish-precursors reproducing by spawning simpler (conceptually egg-like) versions of themselves, eventually evolving into egg-laying fish, and then egg-laying land-based animals including the dinosaurs from which birds developed.

So, maybe the best answer to "which came first, chicken or egg?" is "fish".

The question is asking if the first chicken hatched from a chicken egg (the egg came first) or if the first chicken hatched from an egg of the animal that laid the egg (the chicken came first). Of course, it is just a thought experiment that is ultimately unanswerable. There is no such thing as a distinct chicken or distinct chicken egg.