Baloo: You better believe it.
Bagheera: This will take brains, not brawn.
Baloo: You better believe it, and I'm loaded with both.
Mowgli: Oh, Baloo, I wanna stay with you.
Baloo: Certainly, you do.
Bagheera: Oh? And just how do you think he will survive?
Baloo: "How do you think he will... " What do you mean how do you think he... He's with me, ain't he? And I'll learn him all I know.
Bagheera: Oh? That shouldn't take too long.
Answer: The animals considered man a strange creature and did not understand their ways, like wearing clothes and shoes. They were scared when Mowgli brought them fire. They only knew jungle ways, they figured the humans would eat him, like any small creature left on his own. Plus they knew man as a hunter and killer.