Don't underestimate the three arrows, they greatly impacted the battle's outcome.
One side remained unscathed, all engaged in ranged attacks, while the other side suffered casualties.
In warfare, one-on-one and two-on-one are entirely different conditions.
Military strategy hinges on using various tactics to create situations where the few are overwhelmed by the many, thereby gaining a manpower advantage.
Moreover, Flying Squirrels are not Undead; as long as they are natural life forms, morale plays a role. For example, when Zhenjin directly took out the Flying Squirrel leader, it caused the remaining Flying Squirrels to collapse and scatter.
In fact, they couldn't shoot too many arrows.
Excessive archery greatly depleted their physical strength. They were all temporary archers and should allocate more energy to close combat, or else the losses would outweigh the gains.