#sexual identity

If you are going to be very realistic here about the mentality of being a conservative that is homophobic, transphobic etc or isn't that but believes it should be shut up about and done behind closed doors, you would typically hear or imagine them saying (in their own heads at least):

"These fucking ABC blablabla alphabet soup types, just shut up, we got the gays and the lesbians leave it at that."

They resent the complexity and often assert that it should either have stopped at B or T.

The I stands for intersex people who were previously forced to either blend in with their gender (they almost always try to appear female because often the body of any intersex person is closer to female as that's the template of a fetus, if you didn't know, it's why cis men/boys have nipples and why the penis head and forskin is based upon the clitoris becoming the head and the lingering labia around it becoming the foreskin).

Intersex people have the absolutely psychologically irrefutable and biologically indisputable struggle of coming to terms with not fitting in with either gender. That's because they literally are not either sex fully. At times, there are girls/women with a lot of androgen that quality as I despite being XX but even then you would understand if we lacked hormone treatment, what they would feel and go through being extremely masculine, having brutally heavy periods and other problems as a result of not being hormonally feminine enough to match their sex, not just gender in that case.

If you are confused what I just said, Intersex can indeed mean the XXY chromosome type and others like that but they are only 0.02% of the human population or so it is estimated. Instead, often there is an extension of XX humans that were extremely high male-hormone (androgen, one androgen is testosterone but cis women produce a different androgen as they lack testes, yes even very feminine women produce some androgen, it's how their muscles aren't so floppy and bone aren't too extremely soft nor brittle etc).

Generally a man who was femme never qualified as intersex until either due to emergency surgery or significant anomaly, his testicles didn't function as they should and he really starts to look and seem physiologically emasculated to a significant degree that harms his strength and wellbeing.

Intersex struggle was the most objectively irrefutable of all of them, yet it only got put in recently. From start of humanity to now, intersex people have been bullied, felt weird and had significant struggles trying to feel that they belong with the pronouns and gender they're assigned.

They are also the primary reason that the hormones trans people take advantage of now with their treatments, exist at all. They developed the hormones to treat intersex people and regulate their hormone levels.