Ganesh Chaturthi is a ten-day Hindu festival celebrated to honour the elephant-headed God Ganesha's birthday. He is the younger son of Lord Shiva and Goddess Parvati.
There are two different versions about Ganesha's birth. One has it that Goddess Parvati created Ganesha out of dirt off her body while having a bath and set him to guard her door while she finishes her bath. Shiva who has gone out, returned at that time, but as Ganesha didn't know of him, stopped him from entering. An angry Shiva severed the head of Ganesha after a combat between the two. Parvati was enraged and Shiva promised Ganesha will live again. The devas who went in search of a head facing north of a dead person could manage only the head of an elephant. Shiva fixed the elephant's head on the child and brought him back to life.
Ganesha is honoured in the start of rituals and ceremonies as He is considered the God of beginnings. Episode related to this goes like:
In the beginning, a question was raised among the deities as who is to be revered first in all puja and religious act to remember God. All deities went to Brahma (creator of the universe). Brahma told that whosoever first completes the round of the earth, he will be considered worthy to be revered first in all religious activities. All deities riding on their vehicles started to take round of the earth. Ganesh Ji (called Lambodar also) had heavy body and his vehicle was slow moving rat. All other deities had fast moving vehicles like birds, horses, elephants and chariots etc. How Ganesh Ji could compete in running with other deities?
Ganesh Ji consulted Narad Ji. On advice of Narad Ji, he wrote the word “Ram” (the name of the Lord) on the ground and took seven rounds of the word “Ram” on ground and reached Brahma Ji. Brahma Ji declared Ganesh Ji worthy to be revered first among all deities because the Ram name is also real form of Lord Ram present in every particle of the earth and the whole universe. By having round of Ram-nam, Ganesh Ji had completed the round of not only the earth but the whole universe.
There is another version also that Ganesha took round of His father Lord Shankar & Mother devi Parvati representing the whole universe and reached Brahma who declared Him winner. Thus Ganesha established the supremacy of name of God or Avatar even personified or unpersonified.
According to Baba Ganesha is the first Avatar.
Baba has said, “Love God and become God. I am God and In order to love God, love Me.” I am your father and mother both”. If one loves or serves a Sadguru or Avatar one he is loving and serving the whole universe. Avatar or Sadguru has universal body and mind and He is present in everyone living and nonliving bodies at all levels of consciousness. Whole universe is embodied in His universal body which is His Virat Swarup which Krishna showed to Arjuna. Everything animate or inanimate in universe is manifestation of God. Therefore, anything can be accepted and revered as God in its finite form. Personified God in Human form (Avatar or Sadguru) is most easily and convincingly acceptable by human-kind. This is well accepted in our Hindu philosophy or religion.