The Time Machine, by H.G. Wells

Set in the distant future of 802,700, a time traveler discovers a radically transformed world where humanity has evolved into two distinct species: the Eloi, a gentle and childlike race, and the Morlocks, who dwell underground and exhibit predatory behavior. As he navigates this strange new society, he confronts themes of evolution, class struggle, and the consequences of technological advancement, ultimately questioning the fate of humanity.