In archeology there are artifacts, which are items made or modified by humans, but there are also manuports, which haven't been modified but are found far from any possible origin point and there's no explanation besides somebody carried it there. Manuports include things like stones, fossils, and seashells, and have been found in deposits as much as three million years old. So yeah, apparently the oldest human activity for which we have evidence is Picking Up Cool Rocks.