In "War for the Planet of the Apes," many humans have lost the ability to speak due to a virus known as the "Simian Flu." This virus, which initially affected apes, caused mutations that led to the decline of human intelligence and speech capabilities over generations. As a result, the remaining humans are mostly mute, relying on gestures and limited vocalizations to communicate. This reflects the broader theme of the film, showcasing the evolving dynamics between apes and humans in a post-apocalyptic world.

"War for the Planet of the Apes" was not a flop. Released in 2017, it received critical acclaim and was praised for its visual effects, storytelling, and performances, particularly by Andy Serkis as Caesar. The film grossed over $490 million worldwide against a budget of approximately $150 million, making it a financial success. It also earned several award nominations, including an Academy Award for Best Visual Effects. Overall, it is considered a strong conclusion to the rebooted trilogy.

In "War for the Planet of the Apes," Nova is a young girl who is mute and represents the remnants of humanity affected by the conflict. She is found by Caesar and his group of apes while they are on their journey. Nova forms a bond with the apes, particularly with Caesar. At the end of the film, after a climactic battle and the death of Caesar, Nova is left with the surviving apes. The film concludes with her symbolizing hope for a new beginning in a world where apes and humans might coexist peacefully.

No, Koba is not alive in "War for the Planet of the Apes." In the previous film, "Dawn of the Planet of the Apes," Koba is killed by Caesar during their conflict. His death has repercussions in "War for the Planet of the Apes," as Koba's actions and ideologies continue to impact the dynamics between humans and apes. The film explores themes of loyalty, revenge, and the consequences of past choices.