...if you constantly remind others you are way better than they are (because you are a god and they are mortals for example), even if it's true, you still strongly come off as bragging a lot. At least, it's how I was raised to understand it.
For better or worse, humility wasn't part of Thor's personality.
It's kinda of like Jaco Pastorius- The World's Greatest Bass Player. He would go around to all the Jazz greats and introduce himself this way and they would essentially tell him to f*ck off or something to that nature and then.... They Heard Him Play. Jaco always said: "It Ain't Bragging If You Can Back It Up!!!" When written by someone who gives a sh*t about him- THOR BACKS IT UP!!!! (and then some).