The initial premise isn't too bad. There are some problems. For example when the science on recovering and using A(ancient)-DNA gets better, you aren't going to see these types of experiments in North America, or Europe as in both surveys show a very large amount of resistance. But rather in east Asia where the surveys show a lot more borad public acceptance of human DNA experimentation.
There is also an issue with the way the Neanderthal's boy's intelligence is dealt with. We know that on broad averages individuals and population groups with more Neanderthal DNA input have better spacial intelligence and comprehension of metaphor and symbol -- not less. In that sense this film inverts the science. Neaderthal most likely extinction was caused by competition and with Homo Sapiens with Homo Sapiens key advantages being in long, medium and short burst running speed and a couple of other attributes, including greater sexual dimporphism, that led to better specialization.
but those are not the main problems with this film. The main problem is shoehorning an interesting science fiction piece with a tired melodrama of a kid being different, wishing they were not, and then acceptance. it makes this film a hallmark card/lifetime channel trope that isn't even above average in that field.