I'm not even sure why I am even humoring your nonsense by replying to it, but here are some things you may want to consider:
Maybe because I will also be respecting you and taking you seriously? Rather novel for this forum, but why should we not start a mini-trend? 
1. There is absolutely no reason to suppose that blacks are a mixture of Homo sapiens and Homo erectus. All modern humans share at least 99.9% of their DNA, so even if the two species hybridized with each other their genetic contribution would have been insignificant. Furthermore, any hybridization of these two species in Africa would have occurred before Homo sapiens[/i] migrated out of that continent and diversified, so if blacks are hybrids then that would mean we all are.
I am guilty of using a relativist argument:
"If neanderthalensis could breed with sapiens, then so could erectus"
"Therefore they were different races, not species"
Still, it is just something I want to put out there. Nothing personal against anyone.
Nevertheless, it is hard to prove either way, is it not? According to my hypothesis, erectus, neanderthalensis and sapiens were different races, not species. The man who left Africa could have been more sapienoid than erectusoid, the one stayed behind, more erectusoid than sapienoid. Yes, we are all descendents of hybrids, but in varying proportions. That is the hypothesis. Then you have separate developments. Racial differences occur in often harsh environments, their end results would be fatal and are never actually completed.
Example: Blondism, the end result of which is fatal albinism.
2. Five inches of difference, if that is even true, is hardly significant given the huge amount of variation in normal human brain size (the average size, by the way, is about 85 cubic inches the last time I checked). Brain size has little to do with intellectual abilities; this has been known to science for a long time. That is why people with primordial dwarfism who have brains 25% as large as an average human brain generally have perfectly normal intelligence, and why Homo floresiensis was able to make stone tools and use fire with a brain the size of a chimpanzee's. Albert Einstein's brain was below average in size; it was studied extensively after he died and it was stolen.
There is a correlation between brain size and IQ, in today's human population, another bone of contention of course.
That is what I am going by, not primodial dwarfs (cute though!) and Albert Einstein. I am looking at the analysis lots of a wider field of data, so I think that you might be at fault in this particular instance. I am also being relativist in looking at the current human population and comparing it to erectus, but then, according to my hypothesis which is that erectus, neanderthalensis and sapiens were different races, that is perfectly reasonable...
You have picked out extreme examples though, if you were writing an academic paper, you would hardly use arguments like that would you?
3. Adding to that, Homo neanderthalensis had a brain that was on average larger than a modern human's, and yet we're the ones who are still here today. As stated before, there are much more important things than brain size when it comes to determining an individual's intellectual abilities.
Cro-Magnon man also had a larger brain than modern man, he needed it.
Just as well, it was fr....eeeeee......zing!!!!!
So, we have another factor in the equation and that is temperature.
Autistic people often show extreme sensory tolerance to cold temperatures.
3. There is no direct evidence that Homo erectus was black. We don't have mummified specimens. For all we know, they could have been light-skinned and dark-haired like modern Pan species. And if they were black, what the hell does that have to do with anything at all? The only thing skin color can tell us about a person is how much sunlight their ancestral home had. Just because some populations of modern humans have dark skin and some species of extinct humans had dark skin doesn't mean one is "less evolved" than the other. Each one has optimally adapted to its own habitat over long periods of time. It is likely that our forest-dwelling ancestors even farther back (10+ mya) had light skin like most other primates. By your reasoning, would it be fair to argue that light-skinned humans are more "primitive" than dark-skinned humans?
There are certainly some people who try to make these arguments, if you look at those first three pictures and the video, you can see the inference.
Certainly it is likely that white people evolved as such as a result of forest-dwelling and that extreme blondism occured as a result of Northern adaptation and food availablility.
I do not indulgence in the sort of skin colour racism and accusations of primitivism and inferiority/superiority, but you can find fora where this is endemic.
My special interest is meta-Germanic preservation and my forum is occasionally invaded by racist Indians and others who come to call us 'primitives' and 'savages'.
I could care less, I am just interested in preservation and conservation and being proud and accepting of my primitive ancestry is part of that.
Northern/Central Europeans are largely Cro-Magnoid and nordoid going on what evidence we have so far. You may find this website interesting:
http://www.nordish.com
There is a race gallery on this website which shows the differences between these two meta-groups.
Personally I think that it is unlikely that neanderthalensis and Cro-Magnon man interbred, although we did share similar selection pressures for a time, which would account for similar and subsequent developments.
I think that it is likely that the genes which create autism are rather like the genes which create sickle-cell anaemia in populations which are afflicited by malaria, and that Ice Age conditions were a selection pressure which encouraged their prominence in the Upper Paleolithic survivors who genetics live on in the Cro-Magnoid populations of today.
I have a deep affilliation for Cro-Magnoid cultures and their gentle ways of living and natural tendency towards parity and mutual respect between the sexes. Finnish, Irish and Berber peoples are very interesting to me. Beautiful artisan traditions, and the most incredible women.
In the 'primitive' Cro-Magnoid Guanche culture of the Canary Islands, women were held in such esteem that insulting a woman whilst being armed was a crime punishable by death.
Interesting is it not?