However, there are other laws with constitutional significance. The Statute of Westminster, and the Australia Act.
But, most rights are guaranteed by Common Law, that is, any precedent or judicial opinion in any Commonwealth nation can be used for grounds that a right should be preserved when a decision is being examined by the High Court.
Consider the fact that we are in the middle of an ongoing constitutional crisis, for which the political class knows an amendment is the only effective solution, but nobody in either major party wants to even try.
This isn't a constitutional crisis in the 'dismissal' sense.
It's just the operation of s44 of the constitution causing a headache for parliament. Its been found that many of the parliamentarians are dual citizens, which is forbidden, and their seats in parliament have been nullified by the high court.