There are Jungle Book mangas, with the most famous examples being the Fujiko Fujio version done in 1958-59 and the excellent Julien Choy version with all the stories in the 2010s. Jiro Kuwata of 8 Man and BatManga fame also did a Jungle Book manga at only nearly 17 years old in January 1952, so it’s probably the oldest jungle book manga that few people have known of even in Japan.
Kyuuta Ishikawa also made a Jungle Book manga from 1961-62, albeit it’s a spiritual remake based on the first Classics Illustrated Jungle Book with Alex Blum’s artwork. There were two competing jungle book mangas, one by Takao Ito released very late in the year and another one by Ken Segoshi made for Shueisha’s own Omoshiro Bunko collection. All the manga versions of Mowgli wear loincloths.