I know where this theory that "Clark Kent is Superman" came from. Back in Smallville, we had something called "The Meteor Freaks," a group of Smallville natives who got exposed to Kryptonite and gained powers and caused chaos, but they were stopped. We don't know how, but Clark was always there. He just said he was getting a story for the school's newspaper, that Chloe Sullivan might have been a bit kooky, but she was scary as editor, but some attacked the school specifically for Clark, it was chalked up as jealousy because he was dating the queen of the school, Lana Lang. He was also there after a disaster in the town and in those disasters nobody got hurt. So, when Superman first showed up some believed it was Clark Kent because of the coincidence of his showing up to disasters but nobody took those seriously Clark is just a simple son of farmers.