The worlds of Kingdom Hearts are obviously based on various worlds from Disney films, but I wouldn't count the Pridelands world seen in the second game or Sora as part of TLK. Here's an excerpt from the
Universe of Kingdom Hearts page on Wikipedia which should clear up the confusion regarding Sora (emphasis to the last sentence added by me):
[quote]Those who travel between worlds are advised to limit their interactions with the inhabitants of foreign worlds in order to maintain the world order.[33][34] For this reason, the main characters change their appearance in certain worlds to avoid standing out. In the worlds based on The Little Mermaid and The Nightmare Before Christmas, Sora, Donald, and Goofy transform into undersea creatures and Halloween monsters, respectively.[35][36]
For The Lion King, they transformed into animals because Nomura felt that it would appear odd to have Sora and the others interact in their standard forms, since no humans appear in that film.[/quote]
So he's more or less a human disguised as a lion.
[quote="daantje"]wow I googled him there are so many fan arts of Sora as a Lion! that is very cool does Sora appear adult in the game or only as a cub?[/quote]
Since Sora is 14-15 years old in human years during Kingdom Hearts 1 and 2, he was probably meant to be a young "teen" lion. I don't know if many people have heard of Sora-lion but
haven't played Kingdom Hearts too, but it seems like the TLK fandom got pretty excited when he was first introduced.
(I also find his name rather amusing, since "sora" is also the name of a cute little brown marsh bird found in North America.)