Artie Hawkwing is said to be the most powerful ta’veren ever, but what about Brigitte and the others Heroes of the Horn? Do you have to be ta’veren to be bound to the Horn?
This has been addressed a few times in interviews, which can be found here:
Yellowbeard: I did get to ask a question Terez put me up to.
Brandon Sanderson: His answer was 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.
Matoyak: Heroes of the Horn, are they corrective mechanisms by themselves, or are they corrective mechanisms by virtue of being ta'veren?
Brandon Sanderson: Heroes are not always ta'veren. So, yes, they are corrective mechanisms by themselves.
It should be noted that the property of being ta'veren is something a person can have in one particular lifetime, and it won't necessarily be preserved when that person is reborn and spun out again by the Wheel. It's possible that some of the Heroes were ta'veren in some lifetimes and not in others.
It seems pretty clear that being ta'veren is not a requirement. Brigitte gets a lot of page-time and I don't believe that it's stated or implied anywhere that she's ta'veren.