I’ve heard that they is used as a word to refer to people who are non-binary. Since English is not my first language, I’m not sure what the difference is between they and it in these usages.
Of course, I know that it is mainly used for things rather than people. But I’ve simply thought it is more neutral than they. In this context, is it possible to write it to a person? Could this be a rude act? Or is it because it is often not used as a personal pronoun, so it’s confusing?
Indeed, it is rude to refer to a person as "it", which is the pronoun for objects and animals (except sometimes when the animal's sex is known). You shouldn't use it for people.
Singular they (though not universally accepted) has a number of uses:
On Writing SE I evaluated different pronouns that can be used for a non-binary person. Here's the relevant section on it:
It is the pronoun used for inanimate objects and animals (usually, though even animals are given gendered pronouns when known).
Polls (gender census) indicate that some people want to be referred to as it, though I have never seen this, ever. However, referring to a person as it is almost always intended as an insult, an insult I’ve seen used specifically to make real-life trans people feel less than human.
In the media, the same trope is used over and over again for the same purpose: "It" Is Dehumanizing (there are many, many examples, most of which have nothing to do with gender identity admittedly).
Note:
In English, different pronouns are used depending on the animacy of what is referred to. There are three cases:
Referring to a person using "it" is offensive and extremely rude, because it implies that the person is vermin or an inanimate object instead of a true person.
Why is there a distinction between pronouns referring to people and objects? It's simply part of the meaning of those words. Part of the meaning of the words "he" and "she" is that the thing referred to is a person (or animal), not an inanimate object. Likewise, part of the meaning of the word "it" is that the thing referred to is an inanimate object (or animal), not a person.
If you don't know a nonbinary person's pronouns, then you should definitely refer to them using "they"; referring to them using "it" would be extremely rude.
(Of course, as GArthurBrown points out in a comment, there are a lot of common phrases where the word "it" seems to refer to a person. The examples he gave are: "Who is it?" "It's Joe?" "Oh, it's the guy from the auto shop." "It's a boy!" The way that I would think of these sentences is that the word "it" refers not to a person, but to a position that a person is in, such as "standing on the doorstep," "calling me on the phone," or "newly born.")
You will still, rarely, hear people call babies “it” without any negative connotations. This is a vestige of the Old English word for child having once been grammatically neuter, and was more common in the past. The King James Bible does this sometimes (“Take this child away, and nurse it for me ....”) and so does Shakespeare (“If ever he have child, abortive be it, prodigious, and untimely brought to light, whose ugly and unnatural aspect may fright the hopeful mother at the view ....”) A quick Web search turned up current examples like, “Parents with a new baby are almost always asked, ‘Is it a boy or a girl?’”
I’ve never heard of anyone requesting to be called “it,” but I suppose someone eventually will, to be different.
If a non-binary person is introducing themself to others, they will state their pronoun. And if you're not sure of someone's pronoun, you could always ask them — it's just as socially acceptable as asking someone their name.
IME non-binary people's most frequent choice of pronoun is "they". Some choose a neo-pronoun. I don't know anybody who prefers "it".
As others have said, "it" is predominantly used for non-human items, and sometimes for animals. On top of that, historically "it" has been used in a dehumanizing way, because of that nonhuman/subhuman association. There's even a book "A Child Called It" that handles the implicit dehumanization of the word (as well as other forms of mistreatment/abuse). That said, I do personally know a few people who have reclaimed it/itself pronouns for themselves - ie people have used "it" for those people in a mean way, and they embrace it instead of letting the word hurt them (note my use of they/them here is plural, for just one of these friends I would talk about it choosing not to let the word "it" hurt it). The polite thing to do is to use "they" for a person of unknown gender, use "they" for anyone who asks you to use they for themself, and use "it" only if someone has asked for that pronoun for itself. And of course use "he" and "she" for the masses that prefer gendered pronouns for themselves. If you know someone's pronouns, use exactly the ones that person has asked for.
All languages have the resources to distinguish between the male and the female among animal species. It has, after all, always been fundamental to reproduction and until comparatively recently, to social organisation. So it is not surprising that languages have a male and a female gender. Some, like Greek and Latin, had a separate 'non-gender' (in both cases, the word for 'neither', 'oudeteros' <ουδετερος> in Greek and 'neuter' in Latin). AS has already been said, matters got confused as genders were used for the inanimate as well as for the animate. English is one of the languages that, though it does not have gender as a general feature of nouns and adjectives, unlike the European romance languages, and yet, unlike those and other languages, does have a neuter form of its 'personal pronoun'.
I am not aware of any language that has the resources to cater for multiple or binary gender identity. Biologically, the difference between make and female is clear, with comparatively rare exceptions. So the problem is how a language can adapt to the still controversial idea that there are some people who do not wish to be identified by one of the two 'standard' genders. The answer, I'm afraid, is that it cannot. First of all, the idea of non-binary gender is far from widely enough accepted to be integrated into everyday conversation or even formal writing. Second, there is no resource in the language for 'both'. You could use the term 'ambo' to designate the identity itself, but that does not supply a recognisable personal pronoun. There is none available.
So should we resort to the standard gender-avoidance strategy of the genderless plural 'They/them/their'? Well, we could. The trouble is that in that case we should have to become accustomed to the use of this generally plural pronoun as the immediate subject of a singular verb. But how can this happen by any natural evolution, when the English speaking world is far from accord on the distinctions that lie behind it? The alternative, the use of the neuter pronoun, which you mention, poses much the same problem.
If there is a solution, it is probably that the binary person's name will have to be used when their grammatical role is as subject of a verb, and 'them' and 'their' elsewhere. I am not proposing this: only predicting that that this is more likely to have linguistic legs than any alternative.
