Can I use these interchangeably?

Who just arrived?
Who was the one who just arrived?

Who just came in?
Who was the one who just came in?

Who just left?
Who was the one who just left?

Question

Can I use these interchangeably?

Who just arrived?
Who was the one who just arrived?

Who just came in?
Who was the one who just came in?

Who just left?
Who was the one who just left?

Answer

Actually when you use "just" in your sentence, it is grammaticaly correct to use Present Perfect. So you should say: Who has just arrived? Wo has just come in?

Answer

There's a clear difference:  in all three cases the first example could refer to a group. But if you're asking about a single person, they're interchangeable.