It's kind of a mixed bag. Some aspects of Thor's character and story in Ragnarok are true to the comics, but there are also significant changes and creative liberties taken.
The movie Thor: Ragnarok draws its roots from the Marvel Thor comics. It weaves together elements from different comic issues to bring the story to the big screen. The comic influence is evident in the characters, settings, and overall plot of the movie.
Well, the story of Thor Ragnarok begins with Thor being imprisoned. He discovers that his homeland Asgard is in danger because of Hela. Hela is this really strong and evil force. Thor has to fight his way out and ends up on Sakaar. There, he faces Hulk in the arena which is a wild battle. Meanwhile, Loki has been up to his usual tricks but also joins Thor in the end. Valkyrie, who had her own issues, also helps them. They return to Asgard and engage in a huge battle with Hela. It's a story full of twists, battles, and heroism.
The 'thor ragnarok graphic novel' is mainly centered around Thor's struggle during the Ragnarok. It shows how he teams up with the Hulk, Valkyrie and others. There are amazing illustrations of the epic battles, the destruction of Asgard, and Thor's attempts to save his people. It's a great way to experience the story if you are a fan of the movie or the Thor comics in general.
The back story in the Thor Ragnarok trailer shows that Thor is facing a great threat to Asgard. Hela, the goddess of death, has emerged and is bent on destruction. Thor has been away and returns to find his world in chaos. He has to fight not only Hela but also deal with being stranded on the planet Sakaar. This sets the stage for an epic battle to save Asgard and its people.
Well, in the Thor Ragnarok original story, the idea of Ragnarok is central. It's a cataclysmic event. Thor discovers that Asgard is not as invincible as he thought. He meets new allies like Valkyrie. And then there's the battle against Hela, the goddess of death. She's extremely powerful and wants to take over Asgard, which is a major plot point in the original story.
The main characters are Thor, of course. Also, Hulk, Valkyrie, and Hela. Thor is the central figure trying to stop Ragnarok. Hulk is his friend and also an opponent for a while. Valkyrie is a strong female character who helps Thor. And Hela is the main villain causing all the chaos.