Sooo are we or are we not gonna start army building yet?
Yes, it's definitely one of those.
Walls let us control the village, but I don't think an air force is the answer. Maybe an integrated approach like so:
1. Living walls that grow and heal quickly, perhaps a sponge/bamboo or coral/bamboo hybrid.
2. Enough tough infantrymen to deal with breaches, perhaps a hybrid of badger or wolverine with a beetle or turtle.
3. A large number of ranged attackers, because they're simply the best at hurting enemies before they hurt you. Ideally mobile. Perhaps modified bombardier beetles/skunks/spitting cobras/whatever, perhaps archers, perhaps something else. This should be our primary method of directly attacking the enemy.
4. Pests. Maybe a small, adaptable kind of bug that breeds fast, eats fast, and can go from antlike to spiderlike in a dozen generations (a month?). Perhaps with a give mind, both for coordination and control.
5. Air force. This should be small, but it can be deadly. Perhaps start with a bat or bird, then add size and either some kind of ranged attack or enough strength to drop big rocks in their heads. Probably the least important, as it has the most...issues.
6. Skirmishers, Cavalry, Scouts, and other such troops can probably be ignored, but planning is good.
7. Support. It's vital. Some kind of plant that makes a healing salve, a way to make walls to fix breeches or control the flow of enemies, trees that grow metal leaves, stuff like that.