In the 'alice in borderland visual novel', there is Ryohei Arisu who is a central character. Another important character is Yuzuha Usagi. She teams up with Arisu in many of the challenges in the borderland. There is also Chishiya Shuntaro, a rather intelligent and calculating character who uses his wits to survive the games.
Alice is definitely one of the most interesting characters. Her name is in the title for a reason. She is constantly adapting to the strange world she's in. Another interesting character is the Mad Hatter - like figure who has his own set of rules and motives that keep the story mysterious.
Overall, Alice in Borderland is reasonably faithful to the manga. Some minor details might differ for the sake of the adaptation, but the core story remains intact. There are no major deviations that would change the essence of the original manga.