You don't need to get to the 3rd age in AoE 2 necessarily, unless you're just sticking with a certain strategy or playing a certain map that warrants it. There are whole metas around going offensive in different ways at each age - drush (dark (1st) age militia units), scout rush, archer rush, tower rush, etc., before getting into the 3rd (castle) age. Usually you start with a scout, and if you're not using it for hunting then presumably you're using it for scouting and if an enemy villager strays too far from safety you can try picking them off. Better players can steal the opponent's boars or sheep, re-locate your town center with higher HP next to your opponent, etc.,.