Bilbo was an ordinary hobbit who lived his life very calmly and with no adventure at all.
Meeting the mentor
Gandalf informs him that he will be going on an adventure one day
crossing threshold
Bilbo refuses and as a result, Gandalf keeps insisting and brings him 13 other dwarfs to go with him, him being the burglar
allies, tests, and enemies
*riddles*
The mentor of bilbo would defiantly be Gandalf because without him he would have never gone out on the adventure and stepped out his comfort zone, Gandalf is also seen helping bilbo along the way
while on their adventure everyone realized there was smoke coming from a near fire and send Bilbo to investigate. meaning it was his first real important task
thought the book bilbo fails many tests he encounters but he also succeeds in a lot of them. One deadly encounter he had with Gollum made everyone change their mind on bilbo in a good way. Along the way, he also makes a lot of allies who help them for example, the eagles, Beorn, Mirkwood elves, etc.