The souls of the Heroes of the Horn are reborn throughout history, and I was wondering if they have always been reborn. Was Birgitte's first life the one where she actually was Birgitte Silverbow and the actual hero, or was she always reincarnated, since, like, the First Age and all?
My answer is yes. People are reborn throughout history, woven in and out of life by the Wheel. Some of these people eventually become Heroes of the Horn, but that doesn't mean they always were. The Heroes are not a fixed set:
Artur Hawkwing clapped the sniffer on the shoulder. "Sometimes the Wheel adds to our number, friend. Perhaps you will find yourself among us, one day."
-- The Great Hunt, Chapter 47: The Grave is No Bar to My Call
When a new man or woman is bound to the Horn, they will then be spun out again and again by the Wheel as a hero. There's no reason they shouldn't already have been reborn many times before then.
From interview quotes, I found the following tidbits:
no, Heroes of the Horn are not always ta'veren at all in their lifetimes when spun out. Sometimes, they even live normal lives and don't do anything extraordinary, like they sometimes spend their lives as farmers, etc.
This proves beyond doubt that 'normal' people, not great heroes, can later be reborn as Heroes of the Horn. But since it only covers the case when such people are already bound to the Horn, this doesn't conclusively answer your question.
Why are some of the heroes of the Horn referred to by the name of their last incarnation, while others seem to have archetypal names...like Birgitte, who I think has lived more recently than Birgitte. I might be wrong about that though, because we don't really have the details on that.
Maria Simons: I have no clue.