PSA: Kennen shouldn't win against any top lane that can touch him, but still beats bad players
Take this example of a Riven I was generally shitting on. She made contact with me once and dumpstered about 50% of my health before I was out of stun; she could have done more damage, but her animation cancelling wasn't very good and she was too slow to get the last part of her combo.
https://i.imgur.com/tygrDAT.gif
This is how you beat Kennen in lane, and most common top laners can do it. The only ones who really can't are tanks. He has no survivability and no sustain; if you touch him, he loses most of his health.
If this Riven had done this even once earlier while I was harassing her, without her ult, I wouldn't have been able to stay in lane, because doing it a second time with her ult is guaranteed to kill me or force me to use my ult to disengage. Just before this, I did a full combo on Riven under her turret; she could have gap closed me with Q + E + W (~720 range vs. my 550 auto range) and potentially stunned me under the turret if she were fast enough, but instead, she used it to disengage from me after I had already finished the combo.
The only reason Kennen ever wins match ups is because the other player panics when they take harass, and instead of trading, just try to run away and eat free damage.
tl;dr get good.