I do believe it is as simple, and obvious, as that, caps or not ,chimpanzees, aren't persons. I abide Merriam Webster's definition of person. Chimpanzees, may be self aware and possess a modicum of language yet this does not make them persons.
While, I would assert, that all persons are humans, I would not assert that all persons are strictly Homo sapiens but in fact contain a fair bit of Homo neanderthalensis.
One day may come and one day we may be visited by extraterrestrials and knowing humans, it may well be a mortal insult to call them persons. On That Day(tm) the question can be revisited and some will choose to expand the definition of person, others will want to refer to them as what they are, or create and define a new noun.