Okay, so I’ve seen a lot of people get angry at Dumbledore for making the traps protecting the stone so easy that three first years could get past them. But let’s sit back and think about this for a moment…
They were supposedly set to keep out adults. You can’t expect some random witch or wizard to have skills in everything. Only people like Albus, Tom, and even Severus would have the skills necessary to make it past every trap on their own.
Trap #1Cerberus. Hagrid. Going by the book. A lot of people wouldn’t know how to fend off one without killing it. A lot wouldn’t be smart enough to check its feet to see a trap door. The three heads business would be enough to terrify the intelligence from most.
Hagrid accidentally gave Harry, Hermione, and Ron a way to get past him. Pure luck for three first years.
Trap #2Devil’s Snare. Sprout. Going by the book. They drop through the door and land on a tentacle like plant that begins constricting around them and squeezing them to death. Harry and Ron don’t know what it is. Devil’s Snare was taught at the end of the year in Herbology without a physical demonstration and since neither care much enough to check up on it, they didn’t know. Hermione however, did. If she didn’t know what it was and how to stop it, they would have been dead. Simple.
Trap #3Flying Keys. Hooch and Flitwick. Going by the book. Hermione’s spell didn’t work on the door, so they have to resort to something else. Harry has the natural skill at flying that neither Ron or Hermione have. He is also a Seeker and is able to spot the correct key, among the hundred of others, whereas the other two couldn’t. Hermione didn’t seem to do well on a broom and nothing about Ron’s skill was mentioned. Therefore, it is up to Harry to get the key down. He then has to out-fly enchanted keys bent on doing him harm, the moment he touches the broom.
Trap #4Chessboard. McGonagall. Going by the book. Ron has been playing chess for years and is rather good at it. Hermione thinks it’s barbaric and useless and Harry is just really bad at it. Someone is needed to play the game so that they may advance. Ron steps up and ensures that Harry checkmates the other king. Ron is sacrificed in essence.
Trap #5Mountain Troll. Quirrell. Going by the book. Luckily it had already been dispatched by Quirrellmort, so Hermione and Harry did not have to fight it. Pure luck.
Trap #6Potion Riddle. Snape. Going by the book. Harry and Hermione are now trapped in a room with 7 vials of ‘potions’. I honestly don’t understand the riddle. To this day, I and my mother are at a loss. Three bottles of poison, two bottles of wine, one to go forward, and one to go behind.(<— I rhymed!) Hermione revealed logic to be in play and admitted that, 'A lot of the greatest witches and wizards haven’t got an ounce of logic, they’d be stuck in here forever.’ She solved it for Harry in under ten minutes.
Trap #7 (<— Magic number!)Mirror of Erised. Dumbledore. Going by the book. Harry was tasked with getting the stone which was in the mirror somehow. Only a person who wanted to find the stone, but not use it, would retrieve it. Add on the threat of Quirellmort - a wizard with much more 'skill’ than him - and Harry is in great danger.
However, Harry did not do much. He got the stone, told a measly lie, and defended his parents to Voldemort’s 'face’. It was Lily’s protection that saved Harry and the stone in the end.
So let’s recount…
How many singular first years are going to think to look at a three headed, massive dog’s feet? When it is growling at them and ready to attack?
How many would know to play music to make it sleep?
How many would remember what Devil’s Snare is and know the proper charm required to defeat it?
How many would have the skill necessary to fly on a broom in order to get the proper key, while dodging all other keys?
How many would have the skill to play a live game of chess with themselves as a player, and win?
How many could defeat a Mountain Troll on their own?
How many would have the intelligence and understanding of logic that Hermione had in order to solve the potion riddle?
How many would be able to ignore the fact that they are looking for a stone that can make them either extremely wealthy or immortal? To be able to put aside such things? To face a Dark Lord feared by most and deny the chance of helping him even when he offers to revive the parents you never had the chance to know(even though it was a lie) in exchange for giving him the stone?
How many would have that sort of chivalry?
Harry, Hermione, and Ron each had an important part to play in retrieving the stone. They each had a particular skill that got them forward and onto the next task. Of course three first years would manage to make it. Traps #1 and #5 were already taken care of. Pure luck. Trap #2 was all Hermione. Trap #3 was all Harry. Trap #4 was all Ron. Trap #6 was all Hermione(again). Trap #7 was all Harry(again). Hermione doesn’t possess the chivalry Harry has in order to face Quirrellmort and Ron would have been too swayed by greed to succeed in retrieving the stone.
It was a joint effort on all their parts. No normal first year would have succeeded on their own and McGonagall had verbally set the three Gryffindors apart from their fellows earlier in the year when she commented on the taking down of the Troll in the lavatory.
So no, Dumbledore did not make it easy for first years to pass through. Harry, Hermione, and Ron were rather exceptional in that regard(with some luck along the way).
Now while I do not agree with him placing the stone in the school at all, I can admit that the 7 traps for the stone were amazing and difficult. And I reiterate, only Albus, Tom, or Severus would be skilled enough to get past everything on their own without expecting it all first.