It refers to objects, they refers to sentience or the fact of “someone” being a conscious individual rather than just a “something”.
That’s not necessarily true. “They” also refers to objects.
“It” is the third-person singular pronoun that’s used when not talking about a person.
“They” is the third-person plural pronoun. It’s used for males, females, mixed gender groups, objects, and mixed object/human groups. Or really, “they” is the default (or only?) third-person plural pronoun.
Unless you were going for “they” as the gender neutral third-person singular pronoun.
I’d argue that “it” works better for the same reason that you’d usually use “it” to refer to a robot or a computer unless a gender is somehow assigned to it (e.g., through a voice).
Choosing “he” or “she” is hard and not really logical. “They” makes it sound plural, or trying to hard to “de-objectify it”. Kind of like someone refusing to use he or she to refer to someone who hasn’t explicitly expressed their pronouns, but is clearly and outwardly expressing their gender.