No, it was always intended to be lighter.
Per producer Brad Winderbaum: “There were certain things that Kevin [Feige] wanted… [He] definitely wanted [to bring out] the comedic side of Chris, who’s an awesome comedy actor. And [he also wanted] a big fun space epic that’s not married to Earth. Just a fun adventure film that has big stakes, but also has a breakneck speed and takes you on a crazy adventure.”
Collider.com
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Knowing that Thor: Ragnarok needed a far lighter touch, the producers turned to an unusual directorial hire – the New Zealand filmmaker Taika Waititi, fresh off the indie What We Do in Shadows [Hunt for Wilderpeople was still in post-production at the time]. “When I saw Boy, [Taika] became my number one pick,” Winderbaum revealed “It had a combination that we always are striving for at Marvel, which is a great sense of humor but also moments of real drama and melancholy that the characters had to deal with… His movies deal with real serious themes, but you always leave feeling uplifted.”
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Having now spent a couple years on Earth with Tony Stark, Thor’s picked up on this thing called ‘humor.’ “He understands sarcasm in a way he didn’t in the first film,” Winderbaum revealed “We’re bringing all of that personality into space with him. It’s a flip on the fish out of water because now he’s not the butt of the jokes, wandering around, not realizing why things are the way they are. He’s the one looking at the world and bringing a certain sarcasm and irony to this cosmic landscape.”