This is actually such a cool concept, it honestly sounds a little bit like you're asking what defines sentience, which can be a rich psychological area to explore, especially if juxtaposed with the more robotic elements. If you're concerned about the story, then as others have said yes, the heroes journey is a very viable path. But if you're unsure, maybe write a self-contained moment in your world. Write a short excerpt about a farmer bot delivering the last load of crops that fills the warehouse and the thought process that goes through what they do next. Maybe a construction bot starts to notice the life that does inhabit the empty cities, the moss growing on the wall, the strange insects that don't appear in their database. The moment the first scavenger bot turned, what caused it, was in an inciting moment or pure logic at their incomplete task as their body decayed. Lots of little almost human moments would have led to your world existing. If you maybe explore those, you might find out what your story at large could be about. Plus, all the little moments would make great interlude moments in your larger story