So I guess you're fine with calling books "merely paper" because they are a "subset" of paper-based products? And you're fine with calling people "merely animals" because they're a "subset" of animals?
Human language is not based on set theory. There is a huge difference in connotations here.
Context is important, and the word "merely" can be interpreted in multiple ways. In the first case in this thread, I understood "merely mechanical" to mean "only mechanical," i.e containing nothing that is not mechanical. Using that definition, then humans are merely animals, because they're not something that's not an animal. Books are a bad example, because they do have things other than paper (like ink, glue, maybe a plastic or leather cover).
You seem to be using "merely" to mean "nothing more specific than," which is a very different meaning that would not be appropriate when talking about things which are subsets of other things.
If you care about context, I shall remind you that the original question was:
"Are we sure what is being simulated here is cognitive? It seems to me merely mechanical."
This is analogous to asking "are you sure this is done by humans rather than animals?" The question makes sense and is valid. To answer it with "humans are merely animals" would not address the subject at hand and, again, would have specific connotations.
I see that this kind of semantic acrobatics is extremely common in discussions of AI on HN.
Human language is not based on set theory. There is a huge difference in connotations here.