The transgender movement should be differentiated from the gender fluidity movement. Traditionally, transgendered people recognize that gender is binary but innately feel wrong. This isn’t just about wanting to fit into different gender roles, but a deeper feeling of wrongness and uncomfortableness in one’s own skin.
The gender fluidity movement thinks that gender is the same thing as gender roles. If you’re sexually a male but aren’t aggressive, like flowers and fashion, cooking, etc . . . then you you’re not a male gender. If you wake up feeling more assertive one day and more submissive another day, then it means your gender is fluid and changing day to day. To sum up, rather than emphasize that gender roles are not absolute and that it’s okay to be a man who likes things the current culture sees as traditionally feminine (which is something I believe to be true), they prefer to just reject the idea that this person is a gendered male altogether. Or vice versa. They’re female, or something inbetween, or something not inbetween but something new. They just don’t identify in any traditional gender role, therefore they’re not the gender that traditional gender role is usually abscribed to, which is all a bunch of nonsense in my opinion. Gender =/= gender role. You could say the good thing is that they’re trying to stop people from being made fun of for not conforming to traditional gender roles, but the logical basis and social consequences of their approach are just silly.
Hopefully it’s clear how the transgender movement and the gender fluidity movement are different, though of course there are people who believe in both (or reject both).
And let me be clear that I don’t think nature is always clear cut. To start, people are certainly people born intersex in reality, who truly don’t fall neatly into the two binary genders. These people are still very much human beings and deserve compassion and shouldn’t be forced into one sex or another. There are these exceptions. That said, if a human being is born blind, you still understand that human beings in general are intended to have two seeing eyes.