Kung Fu Panda had Po, a giant panda who initially had a well hidden self-loathing so profound that it made his heroes' initial disdain for him feel positively kind
Peter Quill (aka "Star-Lord") from Guardians of the Galaxy had a rough youth: his father was never in his life and his mother died in his presence when he was about 8 or 9. Moments after that, he was scooped up by some aliens who apparently wanted to eat him (though the actual validity of this claim seems to be wishy-washy; Yondu's been lording the fact he stopped them from doing so over Peter since that day but, again, there seems to be a deeper understanding between them as well). Still, despite his unpleasant youth, he grew up to be a relatively well-adjusted Handsome Lech Loveable Rogue who loves pop music from The Seventies (the memoir mixtape his mother gave him) and all around is a jokey, easygoing guy (though, as he qualifies for the trope, he still lives with the pain of his mother's death and this comes up at the end of the movie).
Ultimate Spider-Man: Spider-Man's wacky jokes and quirky personality are what he uses to shield him from a relentlessly unkind world.