Science fiction’s foundations were laid in the 1860s–1890s by Jules Verne and H.G. Wells. Between them, they invented nearly every major trope: the alien invasion, time travel, the submarine, interplanetary travel, and invisibility.
The Time Machine finds humanity evolved into two species: the beautiful, helpless Eloi and the Morlocks who labor underground and feed on the Eloi at night. Victorian class divisions, pushed to their logical extreme.
The War of the Worlds is the first modern alien invasion story. Wells’s Martians defeat humanity with ease. Only biology saves the Earth: the Martians have no immunity to terrestrial microbes.