"Todoelmundoestáaquí."

We also use the expression 'the whole world is here' when a place is crowded

I used: "the whole world is here" and got marked wrong.

Why doesn't "everybody's here" work?

When translated literally, the sentence has the same meaning in English as in Spanish. Reported again.

I agree. It's silly to claim the whole world is present when you're talking about 20 people. Todos and todas are defined as everybody and work as well as "everybody" in English.

super smash brothers ultimate anyone?

I don’t want to say the whole world is here. Is there no other way to say everyone? everyone, please listen... todo el mundo escuchame por favor..??

everyone is here! [insert SSBU theme here]