The bananas weren’t stolen, they were sold to the gorilla in return for seed distribution services. The tree wants the gorilla to distribute the banana seed within a fertiliser package (poop) some distance away. And the gorilla wants calories, which the tree can endlessly produce using solar power. It’s a fair trade.

Didn't the banana plant (not a tree, technically) produce that banana using nutrients stolen from the soil, carbon dioxide stolen from the air, energy stolen from the sun, etc.?

Exactly: the whole system is based on theft, and should be stopped.