The Lion King is something very weird, as the facts contradict themselves.
There are at least 3 stories about a "lion prince" whose name ends in "-imba", and Kimba the White Lion was not even the first.
The story has almost nothing to do with each other, and the name of the MC wasn't even "Kimba" in the original.
Let's check:
Lion King- the son of the king of the savannah, Simba, is born. He's destined to inherit everywhere the sun reaches. His evil uncle, seeing his chances for the throne vanish, kills his brother ina an "accident" and blames the kid. Simba flees, lives with a happy-go-lucky troupe and, when he gets wind of the evils of his uncle, after a bit of insight and penance, comes back to reclaim his throne, learning the truth in the proccess. If you told me it was a Disney version of Hamlet, I'd believe it.
Kimba- the king of the savannah, in order for his subjects to survive, steals cattle from the humans (frees cattle in the English version). The humans hire a hunter, who captures his pregnant wife, lures him into a trap and kills him, with his last breath asking his wife to name the child Leo (Kimba in the English version). The lioness is taken to a zoo overseas, but she gives birth en route, names the cub as she promised and instills in him the ideals of his father. There's a storm, the boat they were travelling on sinks and the cub scapes to land, helped by the fishes. He's found and brought up by people, far from his land, and learns human culture. His mission is then to regain his position and bring understanding between humans and animals. It's a story about bridgeing over differences.
Only things in common:
-MC a young lion (not really weird).
-Prince of the savannah (well, he's a lion).
-They have to regain their rightful position (there would be no story otherwise).
-A merry band of friends (different nature and origin; not like it's not the rarest thing in stories).
-They see the face of a loved one in the sky at some point of the story (different point of time, different meaning, and if that was plagiarism, ancient shamans would be sueing left and right).
-The name ends in -imba... only in the English version and only because it sounds "African". None of the other names shows any similarity, neither in the original version nor in the dub.
Basically, either Disney has invented the less plagiarizing plagiarism ever or people who don't even have a rough understanding of two very different works with only the abovementioned points in common, which are also shared by many non-plagiarized stories before an after, jumped the gun. It happens oftentimes.