You are in the wrong game thread, buddy. NTR is all about immutable traits being the most important thing, as that feeds into the idea of biological determinism that is core to the genre. It's dehumanizing and humiliating, but that's what most people who consume NTR want out of it.
The bull is a dumb creature moved only by desires, without any concept of higher thought. He goes against the convention and limits of polite society, placing copulation and pure animalistic potency above all else, acting like a primal beast conquers without stopping for a moment to think whether that is the correct thing to do or not. The bull embraces the animalistic side of humanity, the one that we actively need to suppress in order to function in our everyday lives, and has no concept of self-criticism. People who self-insert into the bulls enjoy this, as the bull is usually one by birth, as even ones that a woman would never look at in real life (ugly bastards, drug addicts, the homeless, etc) can enforce their will as they wish, for they were born with a mighty penis, and they don't need to do anything beyond this to dominate women, to dominate the social rules that tell them things like "No is no, bro" and crush them with sheer dickmeat.
The woman is a symbol of purity and, sometimes, strength of will, this is why the two most common archetypes in NTR are either innocent and caring wives/girlfriends or tough and authoritative ones. They can be argued to represent society itself, or an idealized version of it, one that is ravaged and taken by those unwilling to follow its rules (bulls will ignore the opinions of the women in NTR, taking what they want without suffering any consequences). They start out "perfect", the ideal that an author sees in a partner, only for them to collapse against the sexual potency of the bull as they are still animals, without a single vector of resistance left open to them from the very start. This sort of humiliation, this rejection of one's humanity and self-determination, is exactly what people who self-insert into the woman enjoy (most of who are men from my experiences, oddly enough, since the meme-y "I read NTR to insert into the chick" response is oddly common, and you see how far away it is from being a mere joke once you start talking with people, even if they don't realize it themselves), they like the loss of control, they like being humiliated and put into a role since birth, one that they cannot escape no matter how much they work on themselves. This is, in a way, comforting, as humans don't fear anything like they do uncertainty.
The cuck is the civilized man, the one who works on himself and does everything correctly. He is usually either kind and caring to the woman, and may or may not be financially secure to provide her good living conditions (there is a bit of variation, as NTR does have several different "templates" to speak of). That man is also intelligent, typically (or at least the narrative tries to pretend that they are, despite the fact that the cuck would actively ignore his significant other getting rawdogged in front of his eyes with only a thin piece of cloth separating them) and put in effort to follow the rules and treat the woman the way she wants him to. All of this ultimately fails, as he was born wrong, he lacks the large penis that would ultimately let him claim the object of his desire, and that is everything that matters in NTR most of the time. People who insert into the cuck like being helpless, they like seeing what is precious to them being stolen, they like being humiliated as an "inferior male", this once again feeds into the narrative of biological determinism that is common in NTR, the cuck is a weak man since birth, and he can never claim that woman who is guaranteed to belong to the birth. This cannot be changed, man has no control over nature, for he is an animal whose position in the pecking order is decided at birth. The bulls will always win, and no feelings that the woman has for the cuck will stop that, they will only prolong the inevitable.
Then there are also the people that want to see a hot chick get plowed by a massive cock, they don't really get emotionally invested enough to warrant any meaningful analysis.
Of course, in real life this is not how it works, human relationships are complex and many things factor into them. Penis size, while important to a certain degree (women will usually want you to be within the normal size for our species, neither too big nor too small, as vaginas usually develop with dicks that like in mind), it's usually glossed over how non-penetrative sex is as important to a lot of women as penetration itself, since a lot of them cannot reach orgasm through penetration alone. In fact, a large penis making you a "real man" is not even a consistent opinion throughout human history, as cultures develop differently and value different things on account of the stimuli that shape them.
