Wow, that's really an expert question.
As far as I recall - but I don't have my books on me right now - the origin of the term "Wizard of the Wood" is never explained,
and Uther's and Sildonis' backstory is never explained/you really have to go to semi-canon sources to find that out.
Now, what I did in MY game was that I made the WotW a hereditary title for the highest-ranking human
mage in the Barony of Vestfold. Also, while my campaign rarely even took place in Blackmoor itself,
it was easy for me not to dwell on that too much. It was always pretty clear to me that the wizard was a man,
not an elf, though.
I also added a title called "Wizard of the Vale", for the lord of the wizard's tower in the Valley of the Ancients,
which was, of course, Robert the Bald.
I am sorry for not being able to answer your question better, but perhaps this gives you a few ideas on how to go on with it.