Hogwarts: Break off the engagement at the beginning and marry Hermione at the back end

My humble opinion is that there is protection, but it is limited.

For example, some normal damage is similar to Neville falling from the sky but only breaking his arm.

It was the height of a three-story building, and it only received so little damage.

(For more information, see the dead Myrtle when the basilisk appeared, and the Hufflepuff that died in Triwizard Tournament.) ）

And at this moment, Dumbledore has been sent to the Ministry of Magic.

The end of the Philosopher's Stone was also written.

Dumbledore went to the Ministry of Magic, only to be rushed back later.

It shows that Dumbledore knew that Quirrell had a problem, but he didn't expect it to be one and two souls.