Mongooses are not very dangerous when it comes to humans as mongooses are non aggressive to humans as long as the human does not seem like a threat to them.
However if a human seems like a threat to the mongoose the mongoose will fight back which means that the mongoose can cause serious injury to a human.
If you get attacked or bitten by a mongoose the wound from the mongoose can cause streptococcal sepsis which can kill you if you do not get medical treatment.
So if you do get bitten by a mongoose you need to see a doctor or go to the emergency room or urgent care because if you do get the sepsis it can be deadly.
Most mongooses though will not attack humans but just be careful when around them and you should be safe.
Mongooses mostly have a reputation of attacking venomous snakes and killing them or at least injuring them so if a venomous snake tries to attack or bite the mongoose the mongoose will attack and fight back against the snake.
The mongoose usually wins the fight against the venomous snake.