First off, I will have to give credit to Kieran, as his video, and article inspired me to do this. I got some info from him too.
At the end of The Lion King, we see the presentation of Simba and Nala's newborn cub.
Since then, the cub has gained some attention and questioning throughout the years, and I am going to solve all of those questions, and the timeline of the cub.
In the script, King of the Jungle, and King of the Beasts, the first two drafts of The Lion King, Simba and Nala's cub was stated to be a male, as implied in the scripts.
For more information, visit; https://lionking.fandom.com/wiki/King_of_the_Jungle
However, when the script was changed, the notation of the cub's gender was changed, and most likely obscured.
In the 1993 draft, the script's final page describes the cub as, THE CUB, implying that the gender was obscured mid-way through production. Since this was the final script before alternations were made, to bring us the film we have today, then the obscuration of the gender remained throughout the final draft.
In 1994, a few months before the finalization of the film's production as well as release, a series of short stories title, "The Lion King: Six New Adventures" were released, featuring Kopa, the son of Simba and Nala. A common misconception is that 6NA were released AFTER the original film, as well as the books intending to be prequels to The Lion King II: Simba's Pride. Yet this message by Alex Simmons proves otherwise.
In this message, Alex Simmons, the author of 6NA stated that Kopa was his creation all the way, unaffiialted with Disney. He also stated that he was unaware if the creators decided to add a cub for Simba and Nala, and he assumed that they did not refer to the books.
So he openly admitted to the canon film being a separate entity from the films.
Simmons also stated that the book (Presumably A Tale of Two Brothers) was meant to be a prequel to the original book, and verified by the publisher, who received permission from Disney itself.
KEYWORD: PERMISSION not AFFILIATION
Also, Alex stated that he assumed Disney didn't take the books canon, but rather based off the film.
In 1994, the film is released and the cub, looking similar to Kopa, is shown. Now some would beleive that due to the similarities, the cub is, or was, Kopa. But a year later, proved to be void.
In 1995, Roger Allens and Rob Minkoff released a commentary tract on the film itself. Near the end, they described the cub of Simba and Nala, as "Fluffy" giving it a unisex name, and obscuring its gender. Since this tract came out AFTER the release of the books, when Kopa was well known, and Disney was aware of Kopa, this proves that Disney itself, specifically the filmmakers denied Kopa from their canon.
KOPA ---=---- Fluffy
So Kopa isn't canon.
Now let's continue the timeline.
In 1998, the sequel to Disney's The Lion King is released; The Lion King II: Simba's Pride.
A cub is shown, which is different than the cub at the end of the first film. Despite this, Disney has stated that Kiara is the cub at the end of the first film.
Now this would lead you to think that the filmmakers of the first film accept the cub as Kiara.
Well that's where you're wrong.
The commentary tract was rereleased in 2003, 9 years after the original film, and 7 years after the sequel.
The original filmmakers continue their description of the cub as "Fluffy" despite the character already being established as Kiara, which implies that since The Lion King II: Simba's Pride, is not canon, as it is not the creation of the original filmmakers, Kiara is not the filmmakers' creation.
Fluffy ---=--- Kiara
In 2015, a new series based off of The Lion King, premiered on Disney Junior, beginning with an hour long special titled, "The Lion Guard: Return of the Roar" which served as the series' pilot, featuring the son of Simba and Nala. People speculate that Kion is Fluffy, yet there is no confirmation; Not from the creators, not from the filmmakers, and there is not implication. The series is set within The Lion King II, so thus this theory would be impossible, as Kiara is implied to be older than Kion.
Fluffy --=--- Kion
All though I accept the cub as Kiara, this is for people who accept only the first film as canon, and not sequels, or spin offs of any sort.
Fluffy is Fluffy.