Neanderthals had non-written language. Try to hunt in groups without it or past down stone tool making without language. Neanderthal clothes were simple cloaks of animal hides. They didn’t piece together multiple hides like Sapiens did. And their jewelry was cheap shells and eagle talons on strings. Sapiens were more elaborate. Neanderthal cave painting shows signs of autism which might be a cold weather adaption. If Neanderthal had Autism Spectrum Disorder, it is really going to be hard to call them non-human.