If the second human didn't know a camera was involved (or what a camera even is), but had instead found a wireless remote control shutter release in his/her possession, and, not knowing what it was, proceeded to inadvertently take photos because the remote made a fun sound (as in the case with the monkey), then I think it'd be safe to say the second human had no involvement with the resulting photos.

We're not talking about a monkey (or human) framing and taking photos. We're talking about a monkey pressing a button because it makes an interesting sound. There is no authorship there.