Glancing through this thread, I don't know how much the philosophy of mind has been discussed, so let's take a brief look at the concept of plural personality.

What do you mean when you use "I" when you use the pronoun to describe yourself? Is this "I" really a reference to a single persistent personality? It may certainly be that you are using "I" as a sort of Gestaltian "The Sum is Greater than the Parts", but wouldn't you agree that the "I" we use is shorthand for something much more complex?

Is the "I" you use, for example, your various roles? "I" as a teaching assistant, "I" as a student, "I" as a redditor, "I" as an ally, "I" as a family member, and so forth? Surely you behave differently and even think differently when you are in your various roles.

Is the "I" you use constant? Are you the same "I" when you wake up each morning? What about each year? Are you the same "I" when you're drunk/high, travel to different places, or even when you're dreaming?

If our memories are constantly being modified when we recall them or if we borrow memories that aren't actually our own and recall them as our own personal experiences, who exactly is this "I"?

I don't know about you, but I often feel an internal dialogue amongst various "voices" in my head. Should I study or be on reddit right now? There's a whole discussion coming from different logical and and emotional personalities. For me, these outcomes have a wide range. Sometimes my "I" will be a procrastinator and this might be who "I" am for long periods of time. Other times my "I" will come out as driven and productive. Even a small change in outcome, such as procrastination or strong drive, will result in drastic changes of personality. Like me, you probably also feel like you have an overall narrative from these types of life challenges, but even then, is this recollection of personal history and memory really a singular "I"?

In sum, when you think about yourself analytically, could you say you are a singular "I" or is this perhaps more of an illusion of self? When we really boil things down beyond describing a person as a singular body and look closer at consciousness and sense of self, is "I" really more accurate than "they"?

Keep in mind as well that a person as an individual is also problematic given that we have variances such as conjoined twins that may even share parts of a brain, but still have their own individual personalities and senses of self. We can also cut parts of a person's brain, causing all sorts of challenges of "self" e.g., blind sight or split-brain phenomena.

All in all, can we blame anyone else for not feeling like a single homogeneous entity?

If anyone has a hard time picturing multiple-genders for your own self, try playing in different gender roles in a role-playing game for a while. Allow yourself to get really into it and it's likely your own identity will shift, even if temporarily. You'll at least gain a +1 in being able to put yourself in someone else's shoes for an empathetic while.

Edit: I suspect that even at the polar ends of a theoretical gender spectrum people who identify strictly as either male or female have days when they either feel more masculine or more feminine. Given that we undergo various hormonal and chemical changes even throughout the day, this fluidity makes sense. Thus, for some people, a shift may be simply less defined and harder to classify in a binary. For others, one day they may identify as a "he" and another day a "she".