1. The trolls are incredibly slow, so you CAN absolutely run away.
2. I did 0 training or shooting of arrows in any wall or stone. Think i used 29 fire arrows and he was dead. a kiting strategy in the early game. Before even getting to bronze age..
3. Hiding behind trees turned out to be even easier.

If anything, my experience is that the enemies are too dumb and easy. But anything is easy once you figure it out.

If you instead want an easier curve you could suggest a monster suitable to be in between the grey-dwarf shaman in and brute in difficulty to the trolls. But i'd go as far as to say the brute is more annoying than the trolls. I use the trolls as tree farmers. Super easy to just lure towards trees then jump away and he cuts all trees for you.