The purpose of placing the Philosopher's stone where it was placed was to hide it from Voldemort. Is there any in-universe reason why it was hidden behind a series of solvable puzzles? It looks like it was set up such that a worthy hero could solve the puzzles and get the stone (there were even written clues!), but surely the point was to hide it from anyone, including capable wizards such as Quirrel who might be helping Voldemort.
Why then not just hide it behind Snape's magical fire and not provide the potion, for example?
I understand that the purpose of the puzzle is to show Harry as a hero, so I'm not even questioning why the puzzles were easy enough to be solved by an 11 years old, but is there an in universe explanation why there were puzzles at all?