In French, especially when using the inversion to pose questions, it is used to be given in the format that you mentioned, Is John here? = Est-ce que John est ici? (without inversion) = John, est-il ici? (with inversion) In other words, when doing inversions for third person descriptions, French language tries to first indicate the subject, followed by a comma, then to use a subject pronoun "il(s) / elle(s)" to do inversion with the conjugated verb. For impersonal nouns or nouns that include both genders, such as "quelqu'un" in your example, French language takes "il" to include the possibility of both genders. --- Bonne journée. / 좋은 하루. / Good day.

I meant "pronoun" when talking about "il," "elle," etc and not "proper noun".

In french, when you ask a question, you cannot combien proper nouns and verbs, so you use an extra proper noun (like "il", "elle," etc.) For example, "Jean a-t-il vu quelque chose?" which you can translate in english to, "Did Jean see something." But you'll notice that there's both Jean and "il." You can't say "A Jean vu quelque chose?" and so you must add the "il". You could also say "Est-ce que Jean a vu quelque chose?". Or even, in daily language, you can transform a declarative sentence into a question. "Jean a vu quelque chose?" which translates to "Jean saw something?". "Jean est allé au parc?" (Jean went to the park?). But you see, it's not really formal to say it like that.