I suspect a category error in these discussions. We seem to be using functional or psychological criteria to assess whether Neanderthals were human in a Biblical sense.
I don’t see how these criteria are compatible with the question at hand.
For instance, there are people existing today who lack the functional and/or psychological traits of many primates, let alone hominids. These deficiencies can be the result of brain developmental abnormalities, injury, disease or aging. However, if we accept that a child born today but lacking a prefrontal cortex, or a sociopath with an organic brain defect, or someone in the late stages of Alzheimer’s are all ‘human’ in the Biblical sense, then it’s hard to understand how such ‘humanness’ has any functional or psychological criterion. At least not one that could drive a clear line between modern humans and Neanderthals. One can ponder which organisms possess souls but unless there is a definitive ‘soul-o-meter’ instrument available, I think it’s a pretty futile task.