Well, the human race IS getting dumber.
That chart is not how excess deaths are presented.
Excess Deaths are weekly deaths, not cumulative (which actually doesn’t make any sense), and compared to the death counts for those particular weeks of 4-5 yrs prior, either averaged, or plotted as individual lines for each year. Not cumulative difference vs one year. This graph is some sort of contortion. Why do it this way? I can’t believe the Australian health ministry tracks like this.
Go to the CDC Excess Deaths site to see how it is properly done. The UK and Israel match the CDC procedure.
As for the vax rollout in Australia date, well, I don’t now how effective the rollout was in terms of how rapidly how many of the population were vaxed and with what kind. I do know Australia were very strict about travelers and they kept death counts down for a very long time via that strict exclusion of the virus.
Then they loosened travel restrictions last year and the virus killed a lot of people. Their max daily death count was about 250 six months ago, almost certainly from the predominant Omicron variant of that time, arriving from Asia.