You don't seem to understand, ok, two big reasons why Neanderthals couldn't be either Nephilim or hybrids of humans and Nephilim. 1. Neanderthals were taller than humans on average at the time, but rarely exceeded 7 feet tall. Nephilim on the other hand were, if we go by the bible, a whopping 14-16 feet tall. Seeing as humans at their shortest still typically exceeded 5 feet (going by Cro Magnons) although there were regional differences, the hybrids of humans and Nephilim should have still been at a minimum 8-9 feet tall, since height on the genetic level is determined with slight favor towards the same sex parent but otherwise roughly equal, and also a matter of eating habits. However, chances are such hybrids would be weaker than normal humans or Nephilim, as human physiology doesn't support being that tall, as is seen with the relatively shorter lifespans of humans who get really tall like that (the person who holds the record for tallest human was 8' 11", and died at the age of 22, though likely would have died even younger in the hunter gatherer societies of the past. Thanks to the shape of our skeletons, humans can't get much taller than 6 feet without having increasingly severe joint and back problems, the strain on our bones too great). 2. More importantly, Neanderthal DNA is too different from human DNA, which is why we now know they weren't a human ancestor. There is even the possibility humans and Neanderthals weren't breeding compatible. Plus, hybrid animals lack a certain sort of structural consistency that we see in pure species, which would easily be seen in Neanderthal skeletons if they really were a hybrid of humans and something else, but their physiology is not suggestive of that.
