Onion Ring Knight

Well, Thoros did manage to fuse various of Lord Beric's body parts back together, close holes in his flesh from lances and swords, etc. It just worked a little less well each time, and worked as well as it did because he was "freshly dead." Cat's corpse was three days gone and waterlogged before she was raised.

I don't think he is "definitely" anything, let alone a "legitimate human being" after Qyburn's work in the black cells. Heck, he may not even have a head inside that helmet! I've read DANCE twice and never gotten that impression at all. Time will tell on both of your assertions but they're certainly not givens.