I was thinking that too. Could just be a person who had a Scandinavian parent and an African parent.
The Iberian Peninsula is a logical meeting-place for darker-skinned Africans and European types. This was, after all, only around 7,000 years ago.
Or maybe he was simply a result of natural gene mutation caused by early exposure to gamma radiation from a spider bite. Or am I getting the Hulk and the X-Men and Spiderman combined and then flipped backwards in time by H. G. Wells? I can truthfully say that my explanation has a degree of scientific merit un-matched by everything else I’ve read.