Avengers: Endgame, which brought together all the active superheroes in the MCU to defeat Thanos and bring back half of life in the universe.
In order to fulfill his plans of bringing balance to the universe, Thanos had to battle the Avengers, Guardians of the Galaxy, and other MCU superheroes on Titan and Earth and some of them came close to stopping him from snapping his fingers. The team in Titan almost managed to take the Infinity Gauntlet away from Thanos, but Star-Lord’s (Christ Pratt) reaction after learning Gamora (Zoe Saldaña) had died ruined their plan. Later on, during the Battle of Wakanda, Thor arrived with his new weapon, Stormbreaker, and managed to wound Thanos by stabbing him in the chest, but that wasn’t enough to stop the Mad Titan from vanishing half of life in the universe and bringing “balance” to it.
Thanos famously told Thor he “should’ve gone for the head” right before he snapped his fingers, which led Thor to truly aim for the head at the beginning of Avengers: Endgame, though that wasn’t enough to shake off the guilt from the first attempt. However, Thor’s plan to defeat Thanos in Infinity War was bound to fail because he shouldn’t have gone for the head either: he should have aimed for Thanos’ arm.
Why Thor Didn't Go For Thanos' Head In Infinity War
Thor’s decision to stab Thanos in the chest instead of going directly against his head to kill the Mad Titan was an important decision not only for Thor’s development but also for that of the Infinity Saga. Speaking to the snap wouldn’t have happened (which wouldn’t have been ideal in-universe, obviously), and that through the choices that the characters who “are feeling immense pain” make, the audience can learn to empathize with them because “they can grow through stories”.
Thor is known for being impulsive and letting his emotions decide most of the time, so taking that into , it’s not surprising that he didn’t think his plan well and ended up massively regretting what he did for years. Had Thor aimed for Thanos’ arm (the one with the Infinity Gauntlet, of course), he would have stopped the snap, severely injured Thanos, and would have still gotten to gloat as he did with not going for the head. Of course, this would have taken Thor: Love and Thunder, so ultimately, that “bad” decision led to good changes in Thor and the biggest adventure the MCU has seen so far in Avengers: Endgame.
