Got these (notes) provided by my school..

Humans will take any chance to reduce complex and nuanced psychology into rigid, prescriptive labels. It's all astrology, only the flavor of the meaningless noise changes.

Introverts: These are usually people of high intelligence who prefer their own thoughts to listening to a bunch of babbling idiots. They tend to develop close relationships with other bright people, and often decline social invitations from oafs.
Extroverts: These are usually people of average or below average intelligence who have difficulty learning new things because they seldom shut their pie holes long enough to hear what others are saying. They tend to share their ignorant opinions with everyone they meet.
- You have gone entirely in the other direction. And both are bullshit.
  
  I think that was the point
  
  you have discovered the joke yay
- Hahahaha, awesome!

Absolutely horrendous. Please never listen to whoever gave you that. I am very serious: that shows such a lack of understanding anything about people, whoever is using this as a teaching material should be fired and banned from working with children. But they won't, because toxic bullshit like this is what administrators love.
I am really sorry this is your educational experience. It is not supposed to be like this. Introversion and extroversion are just stupid labels that try to make things easy. Those labeled introverts are often the most generous, thoughtful people who actually listen to and cooperate with others.
- Even better, email the school with a well-referenced correction.
- I think people have to come to the conclusion that noone fits a single label at all times. I often hear takes like in the OP from young teenagers who are just starting to grasp a concept.

This was pointed out in another comment but I will basically echo it to just give that call a boost: Point your instructor to well-regarded sources for introversion and extroversion, and let them know that the labelling in their note is not only inaccurate, it falsely attaches a wrongly defined word onto problematic behaviours that have nothing to do with what introversion and extroversion is, which is not good because it propagates a false narrative.
If your instructor doesn’t seem cooperative and insists on being correct, talk to other instructors that you trust, or even go to those with more authority to tell them about the issue. If you can’t get anyone to actually do something, I suggest you change schools immediately, and call the school out for what they did.
Maybe it’s just one of those days, but I have no tolerance for this sort of false narrative being spread, even if the original intention is innocuous, and especially in a school. Being forced to act in a certain way that deviates from one’s personality to not be perceived as a problematic person, especially over a badly-informed opinion, can have lasting negative consequences to children and adolescents. I’m tired of seeing introverted friends and family members suffer over the fact that they’re introverts, to the point where they will deny being an introvert and even echo these sorts of statements in order to blend in.

My so-called introverted friends never want to go out clubbing on a Tuesday night because they only worry about the future like "Oh, if I go out with you tonight, then I'll be a zombie at work tomorrow". Like, live in the now and care about other people, like me!

Self-centered? Hahahahaha
While it's the extroverts that never "shut their pihole".
FFS, being self-centered (in the selfish sense) occurs in both groups/all along the spectrum.
What maroon wrote this drivel?