Earthquakes, hurricanes and floods are all territorial forces. Not everywhere on the earth has them. Humans have brains. When humans use them correctly, they can usually help prepare themselves for these situations. Bacteria? We have immune system. The only reason a bacteria that humans aren't prepared for surfaces, is when humans are living unhealthy slobbish lives to create environments suitable for sustaining deadly viruses like this.
Natural diseases and sicknesses all have cures that grow straight out of the ground, if humans are intelligent enough to do some research. Aids, and other ridiuclous so-called in-curable diseases are usually biologically created for warfare or genocide.
Animals? Easy, you see a lion? Stay the fuck away... rattle snake? Stay the fuck away. Don't want predators coming to your camp? Stop cooking meat and livestock. Eat what grows from the ground. Everything contains protein, even if it's a small amount. Humans weren't always eating meat, so how did they survive before they discovered fire? There's no excuse. Life is not handed to anyone, but it's not impossible, and if you're mentally capable, it's not really that hard. Yes, there's obstacles... but there's more than enough solutions.