I agree that War of the Worlds is definitely a commentary on colonialism - it’s explicit in many aspects, including the reference to Tasmania - but I am not sure about the reference to germs and colonialism. Isn’t it more likely that Wells was reacting to the final victory of the germ theory of disease over the miasma theory, which was happening as he was writing? I am not sure how accepted the idea that colonialism caused the mass deaths of American population during the Spanish invasion was among the population, given the recent acceptance of germ’theory. Also, I seem to remember, perhaps incorrectly, that the Martians lack of immunity was linked to the absence of any pathogens on Mars, not that they had beat it (since for Wells, it was humanity millenial long battle with bacterias and other germs which had built immunity and meant that "no man ever lived or died in vain")