I had a quick look at the Australian constitution

And did a search for the word Citizen. It only appears twice and refers to citizens of other powers. Not Australian.

I quickly scanned through the constitution and it often refers to people, but it does not define people.

It's quite possible I have missed something or that there are other laws about citizenship.

But as far as I can tell , according to the Australian Constitution, none of us are citizens of Australia.

However according to ChatGTP:

In the Australian Constitution, the term “citizen” isn't explicitly defined. However, it does refer to the qualifications for voting and eligibility to stand for Parliament. The Constitution largely relies on the legal understanding of citizenship, which has been further clarified through legislation and court decisions.

Because of the eligibility to stand for parliament, I previously wrote this

See also my take on Laws