ETA: The Trial of Logan Gruver

Logan Gruver doesn't mean to commit the first murder in history-it was an accident, he swears. But now, he has introduced violence millennia early, escalating humanity's destruction, and is about to go on trial for the first time-travel murder ever. All Logan wants is to find purpose in his life, stuck in a house with abusive parents who are always comparing him to his deceased sister, and trapped in a stalemate banking job where he feels invisible.
So when he wins a shot at traveling five million years into the past as a volunteer guard, Logan jumps on the opportunity. His newfound freedom is a breath of fresh air. He even finds love with a charming traveling journalist, Giselle. Unlike anyone he's ever met, she challenges him to learn more about himself, and the two grow closer as they journey into the past. Then the curious duo discovers the organization they traveled with is keeping a massive secret: humanity will mysteriously go extinct in the future, and no one knows why.
These vacation getaways to the past are actually an attempt to restart humanity, five million years prior. The bigger problem: the attempt isn't going to work. While trying to save both past and present, Logan makes a grave error that ends in a murder that was never supposed to happen. Now the entire timeline is on the brink of destruction, and Logan may have to make the ultimate sacrifice to save mankind.