Sure this game is old so is it's AI. It's the third game I've played all I can see is that the AI is an ineffective sitting duck on easy level, I've all my time to build better troops and crush my neighbour with werewolves and a super-stuffed hero, however they had a lot more cities, troops and even ships at the first time I met them. I'm still getting how the game mechanisms are running, but you won't learn anything having all the time to prepare to attack the duck in his pond with a Gatling gun. Should I jump directly on hard to make things a bit funnier ? Is the AI more aggressive and reactive at this point ? Does it actually move from it's main island and expand ?

You could give the Master of Magic unofficial patch a try. It contains quite few AI (and other) fixes.

Just switch straight to Impossible on Large land mass :) It's still easy, but you might get overwhelmed on occasion when the AI gets lucky. Also check out the patch Petrell linked to, as well as my mod which can be found on the same forum.