From what was written about Elizabeth of York (through the eyes of others during the reign of Henry VII and more intimately through Catherine of Aragon), there is no evidence of her being selfish at all. She was gentle and motherly to Catherine of Aragon after the death of Arthur. I don't think she was the type of "I would be queen at any cost" and certainly an incestous relationship with her uncle would not fit her interest at all. Also the timeline, Elizabeth Woodville was already plotting with Margaret Beaufort for a match between her and the younger Henry Tudor. I have no doubt that she would play along for the ride, but her heart would be very far from a romance with an uncle.
In case you haven't noticed, "gentle and motherly," sweet and tender in all her feelings, charitable and pious, a true Christian in all her thoughts and deeds, resolute in her faith, etc., etc., etc. (one could truly go on endlessly), constituted the standard, state-approved description of every English queen from the Middle Ages well though the early modern age.
I find it quite amusing that some of us here, who refuse to accept what they call "Tudor propaganda" about Richard III, are only all too willing to swallow - hook, line, and sinker - quite obvious Tudor propaganda about the first Tudor queen consort, Elizabeth of York.
The fact of the matter is, we know very little about Elizabeth of York, except that she was the most notable pawn in the high-stakes royal matrimonial game between Richard III and the future Henry VII in late 15th-century England.
I tend to agree with Kim, Elizabeth was probably something of a "ninny"... indeed, probably your archetypal dumb blonde. I don't mean this as an insult to blondes (I am blonde myself). But everyone here must recognize that there's a certain type of young, nubile female who's completely caught up in her own sexual attractiveness and appeal to the opposite sex. Face it, it's an elixir, it's power, it's mind-blowing, especially if you're still only in your teens and middle-aged men are acting like fawning idiots around you... The most stable and intelligent, the most pragmatic brain has lost its powers of reason with far less temptation. I suspect Elizabeth's was not the most intelligent brain. Indeed, I suspect she was, as the historic record (admittedly, it's patchy) attests, first completely under the sway of her mother, Elizabeth of York, and then under that of any other powerful personality who came into her orbit (Richard III, Henry Tudor later Henry VII).
I've heard that Henry VII treated Elizabeth rather shabbily. I can't remember where I read this. But it was definitely to the effect that he accorded her very little respect and while he seems to have loved her, in his own fashion, as the mother of his children, he wasn't exactly emotionally overcome by her death. Wasn't he at the very least contemplating asking the hand in marriage of Juana the Mad, the sister of his daughter-in-law Catherine of Aragon, mere months after Elizabeth's death?
As I said in a previous post, I don't think these particular rulers, these kings and princes, queens and princesses, who inhabited the highest ranks of power and status in their narrow little 15th-16th-century royal world, gave much time or thought to ordinary emotions or indeed to any deep emotional attachment to fellow human beings. They seem to me a very cold lot. I doubt we would like them much, if we were somehow to be forced into their company.