Maybe it's off topic and you win the second scn(battle of mylae), but if one day you play it again, try this:
(it's for any level easiest to hardest)
build some docks at the south of the map(2 or 3)
(protect them at all price. You have more chance to fish and build a navy in the south. But train some ship at your dock(north). Later in the game, trade food for gold with merchant ship.)
when the game start begin to scout your island. Why? Find a place to the west where you gonna find gold and stone. The fact : that place has a "natural wall" with cliffs and forest.(only one path lead you to this place) It give you a quiet place to go through the ages and get ressources, but don't let the red player follow you at this point( and they gonna think you're dead if they destroy your first base). Build a storage pit and let some villis there.(It's your second base)Build a new town center at this place if you lose your first base or build a TC at bronze.
A Resume: with this, walls (and towers) are obsolete on your island but builds some walls: It keep the red away of your second base while they try to destroy them(the walls).
Protect your docks (and walls)at the south with war galley, etc.: the red continue to landing at your island and your war boats are the only one to protect them while you work hard in your secret place. And when you are strong enough, go out and get the yellow island!!
After, build a base on the red island and protect this one with defensive/offensive towers!
This scn has two gifts to offer to the player:
-the yellow island(with many ressources)
-the funny place at the west allow(ing) you to play "left for dead" with the AI while you work to reach iron and train a strong army and navy!!
Have fun!