On the Topic of Smasher...

I think that Smasher is a very straightforward character with regards to what he represents in the overall story. Smasher is an uneducated settler that is the stereotypical evil colonist, he cuts off and boils aboriginal ears, keeps an aboriginal woman to rape and abuse, and speaks of said aboriginals as if they're an unstoppable plague while simultaneously being animals to be scared off or slain. He is the simple colonist at its worst, taking what little freedom he is afforded in his new life and using it to impose his immoral will wherever he can. In a more abstract sense, Smasher is vice and hubris, based on his rampant alcoholism, schadenfreude, and motivation of pride.

That being said, I don't believe that the character of Smasher is particularly informative with regards to early Australian colonial history. For me personally, Australian colonialism was one of the instances of colonialism I was least versed in, but there are general categories of colonialism, and so Smasher simply indicated that there were individuals in Australian colonialism that murdered for its own sake. This was true of every instance of colonialism, but one can infer that Smasher's inclusion and prominence within the story indicated a sort of prominence of this type of colonist.

Being generous, Smasher can provide us with the perspective of an individual who was treated horribly and thus treats others horribly whenever he is given the chance. In that respect, he is the stereotypical bully taken to an extreme, as bullies are typically characterized as having a difficult home life, and taking out their frustration and learned behaviors on others. I'm hesitant to expand that reasoning to all colonists that committed myriad evils, but it is probable that there were at least a handful of colonists that were similar to Smasher rather than being evil gremlins by nature.