Odin gets the elaborate myths, but the evidence suggests Thor was the god ordinary Norse people actually leaned on. His weapon is the hammer Mjollnir, which returns to his hand when thrown; his function is protection, he defends Midgard, the world of humans, and Asgard, the world of the gods, against the jotnar, the giants of chaos. Where Odin is subtle and untrustworthy, Thor is direct, immensely strong, quick to anger and reliably on the side of order. That may be exactly why he was popular.
Two kinds of evidence point that way. Thousands of small Thor's-hammer amulets survive from the Viking Age, worn at the neck; they multiply, tellingly, as Christianity advanced, as if pagans were answering the cross with the hammer. And the god's name is embedded in Norse personal names far more often than Odin's. His day, too, stays with us, Thursday is Thor's day.
The myths cast him as the tireless champion. He wades rivers, smashes giants, and fishes for the Midgard Serpent, Jormungandr, the monster coiled around the world, an enemy he is fated to kill at Ragnarok, and to die of its venom nine steps later.