This actually ties in to a bigger theme in Animal Kingdom of the interaction between mankind & nature, and more specifically the tension between appreciation & exploitation of nature, which all the individual lands have: https://twitter.com/marysuewriter/status/1355941961203556355

The Africa area showcases safari animals and has a poaching storyline (which was a lot more explicit in the gruesome and extremely short-lived original version of the safari ride, featuring a fiberglass dead elephant and a race to save its orphaned baby from armed poachers)

The Asia area focuses on loss of habitat. The meta story is that a corrupt ruler once cleared the forest to build a private hunting retreat, and after his death by tiger the people repurposed it into a nature preserve. (The tiger exhibit is set in the ruins of his palace)

Then later they also added a yeti coaster to the area, and the queue explains the storyline that a train was built through the mountain by a shipping company. The yeti attacked, the train was abandoned, now a tourism company is trying to use it again & rollercoaster danger ensues

Even DINOLAND USA has a metanarrative about the tension between research and tourism. The story of the original dinosaur ride is that paleontologists found a lot of fossils next to a tiny town, and a tourism boomtown sprang up around it with themed gift shops and a tacky carnival

And then finally I did a whole video on it and what I think of the execution of it, but the Avatar section has a theme of exploitation of resources and wars fought over the resources, and nature reclaiming the remnants of the war.

Joe Rohde who developed a lot of Animal Kingdom has some really good & dense instagram posts about basically every facet of the park which are really good reads if you have a free afternoon https://instagram.com/joerohde?igshid=i3fswwda87xz

So tl;dr they used an oil rig skeleton as the base of the tree because they needed something that could withstand hurricane winds and also had enough room in the base to house their terrible Bug's Life show but it's a good metaphor for the theme of the rest of the park