Interesting question this which spreads more light on how we think of ourselves than it does on the nature of God.
Logically given the area of the world he came from Jesus should have been semitic rather than truely negroid. The chance of him being a blue-eyed blonde are slim to none. What should be remembered is that the image of Jesus we have in our minds (the physical one not the spiritual one) will be garnered from those images that we have been exposed to over the course of our lives. Consider this one from the 17th century:
this is taken from an Ethiopian text and show a man who is far removed from the "traditional" (ie Western European) image of Jesus.
The Bible tells us that God made man in His own image. It may be true to say that we make God in our own image too.
If you look through biblical images from before the 19th century you will generally get a good idea of what the people wore and looked like at the time the book was made. Thus historians researching costumes in the 14th century will consult bibles made at that time.
Our image of Jesus is heavily influenced by the Victorians and their mass produced images many of which were produced for a propaganda purpose or to pander to the masses. Heck the guy was a carpenter can you really see him as having long hair to get caught up everywhere and nicesoft hands?