I don’t think “the mainland” works as an example of human-centric-ontology (pretty sure the OP approach would consider that an object), but “seat of a chair” might, especially for chairs all made of one piece of plastic/metal. At the very least, it is clear that we can point to things which are not “natural” objects in the OP’s sense (e.g. a particular cubic meter of air), but then the question is: how do we define that object over time? In the chair example, my (not-yet-fully-thought-out) answer is that the chair is clearly a natural object, and we’re able to track the “seat” over time mainly because it’s defined relative to the chair. If the chair dramatically changes its form-factor, for instance, then there may no longer be a natural-to-a-human answer to the question “which part of this object is the seat?” (and if there is a natural answer, then it’s probably because the seat was a natural object to begin with, for instance maybe it’s a separate piece which can detach).
I do agree that there are tons of “objects” recognized by this method which are not recognized by humans—for instance, objects like cells, which we now recognize but once didn’t. But I think a general pattern is that, once we point to such an example, we think “yeah, that’s weird, but it’s definitely a well-defined object—e.g. I can keep track of it over time”. The flower-minus-one-cell is a good example of this: it’s not something a human would normally think of, but once you point to it, a human would recognize this as a well-defined thing and be able to keep track of it over time. If you draw a boundary around a flower and one cell within that flower, then ask me to identify the flower-minus-a-cell some time later, that’s a well-defined task which I (as a human) intuitively understand how to do.
I also agree that humans use different boundaries for different tasks and often switch to using other boundaries on the fly. In particular, I totally agree that there’s some laziness in figuring out where the boundaries go. This does not imply that object-notions are ever fuzzy, though—our objects can have sharply-defined referents even if we don’t have full information about that referent or if we’re switching between referents quite often. That’s what I think is mostly going on. E.g. in your cell-which-may-or-may-not-replicate example, there is a sharp boundary, we just don’t yet have the information to determine where that boundary is.
I don’t think “the mainland” works as an example of human-centric-ontology (pretty sure the OP approach would consider that an object), but “seat of a chair” might, especially for chairs all made of one piece of plastic/metal. At the very least, it is clear that we can point to things which are not “natural” objects in the OP’s sense (e.g. a particular cubic meter of air), but then the question is: how do we define that object over time? In the chair example, my (not-yet-fully-thought-out) answer is that the chair is clearly a natural object, and we’re able to track the “seat” over time mainly because it’s defined relative to the chair. If the chair dramatically changes its form-factor, for instance, then there may no longer be a natural-to-a-human answer to the question “which part of this object is the seat?” (and if there is a natural answer, then it’s probably because the seat was a natural object to begin with, for instance maybe it’s a separate piece which can detach).
I do agree that there are tons of “objects” recognized by this method which are not recognized by humans—for instance, objects like cells, which we now recognize but once didn’t. But I think a general pattern is that, once we point to such an example, we think “yeah, that’s weird, but it’s definitely a well-defined object—e.g. I can keep track of it over time”. The flower-minus-one-cell is a good example of this: it’s not something a human would normally think of, but once you point to it, a human would recognize this as a well-defined thing and be able to keep track of it over time. If you draw a boundary around a flower and one cell within that flower, then ask me to identify the flower-minus-a-cell some time later, that’s a well-defined task which I (as a human) intuitively understand how to do.
I also agree that humans use different boundaries for different tasks and often switch to using other boundaries on the fly. In particular, I totally agree that there’s some laziness in figuring out where the boundaries go. This does not imply that object-notions are ever fuzzy, though—our objects can have sharply-defined referents even if we don’t have full information about that referent or if we’re switching between referents quite often. That’s what I think is mostly going on. E.g. in your cell-which-may-or-may-not-replicate example, there is a sharp boundary, we just don’t yet have the information to determine where that boundary is.