The key point is there is plenty of proof that consciousness is emergent, not structurally baked in. An excellent counterpoint is the "They're Made Out of Weights" post. There are plenty of emergent systems that clearly show intent and what we consider intelligence, like how ant colonies act as a unit.

If you want to get evolutionarily technical, humans are made of cells which began as individual organisms and coalesced into higher life forms. So the concept of a "life form" is very much flexible, so is every capability of a life form, including consciousness.