The Citizenship of Heaven

That night I dreamed I had arrived at heaven. The gates of paradise were shut. Standing outside, I called out: Who are you in there? Hindus?
The answer came: No.
: Then Muslims?
: No.
: Then Buddhists?
: No.
: Then Christians?
: No.
: Then Jews?
: No.
: Then Sikhs?
: No.
: Then Jains?
: No.
Impatient now, I demanded: Then who are you?
The answer came: We are human.

I understood nothing. So is it that one must become human to enter heaven? Or is it that everyone becomes human only after entering heaven?