The Lion King is not entirely an original story. It takes inspiration from various sources and incorporates elements from different tales and folklore.
Well, in the fox and the lion original story, one moral might be about perception. The fox initially saw the lion as this big, scary thing. But as time passed and he interacted more with the lion (even if just by seeing it regularly), he realized it wasn't as fearsome as he first thought. So, it shows how our first impressions can change over time with more exposure.
The main character is surely the clever lion. There may also be other animals like zebras, wildebeests which could be either its prey or its neighbors in the story.
The clever lion original story likely has the lion as the main character. It could be about how the lion uses its wits in a world full of stronger or more numerous opponents. It might be that the lion devises a plan to rule over a certain area without having to constantly fight. It could also involve the lion using its intelligence to make alliances with other animals for mutual benefit, like getting help in hunting or defense.
The 2019 version of Lion King has the same story as the classic one. Firstly, it maintains the key events such as Simba's father Mufasa's death which is a very crucial part of the story. Then, Simba's self - discovery during his time away from the Pridelands is also the same. Also, the final showdown between Simba and Scar to take back the throne for the good of the Pridelands and its inhabitants remains unchanged. The movie stays true to the original story's essence.