The WTS has expressed some opinions in print on the matter.
Most recently, they ran a blurb in the "Watching the World" of 11/11 Awake that clearly implies the writers believe Neanderthals were human, a belief that dates back to earlier publications. This follows the relatively recent Origin of Life brochure, which only mentions Neanderthals and cites a source to the effect that they were 'a true human race.' Presumably because they are too difficult to address in a short brochure, it doesn't even touch the rest of the genus Homo. But, the old Creation book gives a few more clues to their thoughts on the matter:
*** ce chap. 7 pp. 94-95 pars. 32-33 “Ape-Men”—What Were They? ***
32 If any australopithecines were found alive today, they would be put in zoos with other apes. No one would call them “ape-men.” The same is true of other fossil “cousins” that resemble it, such as a smaller type of australopithecine called “Lucy.” Of it Robert Jastrow says: “This brain was not large in absolute size; it was a third the size of a human brain.”48 Obviously, it too was simply an “ape.” In fact, New Scientist said that “Lucy” had a skull “very like a chimpanzee’s.”49
33 Another fossil type is called Homo erectus—upright man. Its brain size and shape do fall into the lower range of modern man’s. Also, the Encyclopædia Britannica observed that “the limb bones thus far discovered have been indistinguishable from those of H[omo] sapiens.”50 However, it is unclear whether it was human or not. If so, then it was merely a branch of the human family and died off.
The Human Family
34 Neanderthal man (named after the Neander district in Germany where the first fossil was found) was undoubtedly human. ...
So "Lucy" is an ape and Homo erectus could fall either way. They say Neanderthals and Cro-Magnons are human, but that is their only logical option without significantly rethinking their views of Genesis since Europeans carry Neanderthal DNA and Cro-Magnons really are just humans.
I suppose a Witness who cared could make they're own judgement on the rest of the fossils, but that is an area few dare to tread. That, and scientists generally believe Neanderthals died out before the time WTS says they must have been created. Cro-Magnons are older than dirt too.