Thanks for your work! The premise was interesting but I think it's best as a one-shot.
Considering how different structurally we are today, I'd wager that most modern humans would die within a month or so. Diseases wouldn't be terrible, I think. As long as someone survives the initial wave, they should gain immunity. Any modern human would definitely change the world though if they can survive past the initial year or so. Introducing agriculture would be key, which arguably would introduce more suffering, but it's a necessary step to take.