Given the context, most people would consider a machine as something designed and built by people. With respect to babies: we cannot do the former (yet) and I think most people would consider the latter to be a bit of a stretch (growth and development is a bit different from the common notion of building, even if it is a biological process occurring within a person).

While someone can probably cite a more intricate machine that can reasonably be held within a hand, the assemblage of features in a phone certainly makes it one of the more complex machines of its size. Especially when you consider how many fields it draws upon. Digital electronics is sufficiently different from RF electronics, the RF spectrum behaves differently (from an engineering standpoint) from the optical spectrum. That accelerometer may be packaged like an IC but MEMS are quite different from a CPU or solid state memory. The list could go on.