I just want to say that the adults in the situation like the teachers and the principal and even the parents all let this continue and did nothing to protect kid being bullied. The fault should fall on the adults more than the kid. How do you expect a kid to have better morals than the adults that raise and teach them?
Speaking as someone who went through my own personal hell in grade school from grades 4-8, kids are vindictive, petty and sneaky.
There's only so much that a teacher or principal could do to mitigate verbal abuse - because my bullies were outright conniving shits. Short of them overhearing the abuse, which tends to be saved for places its difficult to monitor (bathrooms, changerooms, the recess yard and school bus) there's absolutely nothing they could do... It's a game of he said, she said except the bullies tend to have numbers to contradict the loner victims.
Unlike physical abuse where you can point to scratches, cuts, bruises, swelling, welts and/or broken bones, there is no evidence of verbal abuse and harassment. Especially not when you're a solitary victim.
My parents got involved, and it solved absolutely nothing. I ended up switching schools to resolve the issue - by transferring out the middle school I was expected to attend for grade 9 and doing my grade 9 elsewhere. This mitigated many of the circumstances which allowed me to be singled out as a victim because I'd formed friendships and wasn't a social outcast by the time my tormentors merged into the high school system in grade 10.
Looking back, I don't see how the school district could have done much better with the options available to them. It's not like you could waterboard the kids or cane them to extract the truth. The school staff allowed me to stay inside and read, allowing me to enjoy a safe space a few days a week but it served to perpetuate the problem by further isolating me and creating jealousy amongst my peers, fuelling the cycle... Had I been part of a larger school, I would have had a few more options available to me in the form of school clubs fostering different skills or nurturing certain interests - but I was a part of a small choice French school in a small town. Our K-8 had 126 students enrolled and didn't have the numbers to provide intra-school clubs. For context, my grade 12 grad class was 142 students from my high school.
Edit: To further complicate the problem, every time a change was made and the bullies were approached by teaching staff, they would retaliate and lash out at the first occasion when they found an opportunity. It got to the point where I'd rather button down and withdraw than deal with my bullies ire over being "disciplined" (if you can call any of the measures used discipline). Any attempt to help, made every à magnitude worse within a week when vigilance dropped.