Maybe problem in timing. You must use lid when hear ork's steps and screen shaking. If you see ork it's too late to use lid.
The troll destroys the lid. But it stays intact with the talent, providing you've killed the insects which also destroy the lid. If you get troll, and one insect hitting it, there's a danger you lose the game. Otherwise it remains intact. You can also use the other talent if you have stuff in the pot to eat it and give it a small boost.
The troll there's time, despite the footsteps to cover the pot as the troll becomes visible, giving it more longevity. Yea, higher the level, the worst for wear it gets. The main thing is no insects hitting it while the troll is there.
Despite this the demo caps easily as in nothing left to do, except play higher levels pointlessly. It takes maybe 25-30 minutes completing the current content