They're puppy dogs, for the most part...but some puppies bite.
Ball pythons are generally non-aggressive, preferring to curl into a ball and protect their heads from danger, rather than strike. That's where the common name "ball python" comes from.
However, like ANY snake species, they can and sometimes do bite. And occasionally, you might find one that is extraordinarily aggressive. I believe our resident Boid Queen, Tula_Montage, has one that is quite aggressive. It's a snake. If you make a mistake, you will know it, in no uncertain terms. Like any and all snakes, their only "true" defense is a bite. If pushed or confused, it could happen. Most of the time, it is OUR fault, not the snake's.
Their teeth are definitely larger than a corns, but not quite the size of a boas. I got tagged by a full grown BCI many years ago, and it hurt...bad...and bled all over the place. But it was my fault. I've also been tagged by my Florida king before she settled down. Not even close to the BCI bite. Since a BP's teeth are reasonably in between the two described in terms of size, I will assume that the pain from a bite would be as well.
That means that a bite from a full grown BP will probably hurt, might bruise, will probably bleed...but it won't kill you. Probably won't need stitches, IF you don't pull away, but will require a thorough cleaning and probably bandaging. So yea...it will probably hurt a little bit. But it can't be that bad. I'd choose it over a dog bite or cat scratch any day of the week...