People could not fly, at least not without the aid of some tool, such as a paraglider or a flying broomstick. They could not fly by their own power.
Because Filius was so short, he needed Wingardium Leviosa to "fly" so the students could see him.
But strictly speaking, that was not flying either, but levitation, though he could make himself seem as if he were standing on solid ground.
Quirrell had invented a spell that allowed him to fly short distances, and it was both wandless and nonverbal. The only others who could do that were Voldemort and his followers. They turned into wisps of black smoke and flew at tremendous speed, something Quirrell's magic could not achieve.
"So he wanted to try his luck and see whether he could crack Voldemort's spell?" Pomona asked as she drank her "juice." The house shaped like a church spire was a tea shop, but they had not bought their drinks there. There were quite a few bars in this market.
"Filius and I both advised him not to become so obsessed with Voldemort, not to try to pursue him," Minerva said, drinking her "cold water."
"But he wouldn't listen, would he?" Pomona carefully studied Minerva's expression.
"He was so good at nonverbal spells because he had trouble speaking clearly. I don't think that's a flaw worth mocking," Minerva complained.
Pomona recalled those "little Supermen" at school.
"Quirrell was at the bottom of the food chain," Pomona mumbled.
"What?" Minerva asked as if she had not heard clearly.
"Nothing," Pomona said, taking a big gulp of "juice" through her straw.
After leaving Quirrell at the Muggle Artifact Museum, Pomona and Minerva continued wandering through the flea market. There was even a Gringotts here, but unlike the main Diagon Alley branch, which specialized