Similarities between Sri Hanuman and Lord Ganesha

1.  According to Srimad Ramayana, Lord Ganesha had no place among the Devatas.  Only Kartikeya found place among Devatas.  Lord Ganesha was mentioned only Puranas.

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While roaming in the Dandaka Aranya, Sri Rama, Lakshmana, and Seetha enter the hermitage of Sage Agastya.  While going to meet the Sage, they saw the designated places for various Devatas.

स तत्र ब्रह्मणः स्थानम् अग्नेः स्थानम् तथैव च ||
विष्णोः स्थानम् महेन्द्रस्य स्थानम् चैव विवस्वतः |
सोम स्थानम् भग स्थानम् स्थानम् कौबेरम् एव च ||
धातुर् विधातुः स्थानम् च वायोः स्थानम् तथैव च |
स्थानम् च पाश हस्तस्य वारुणस्य महात्मनः ||
स्थानम् तथैव गायत्र्या वसूनाम् स्थानम् एव च |
स्थानम् च नागराजस्य गरुड स्थानम् एव च ||
कार्तिकेयस्य च स्थानम् धर्म स्थानम् च पश्यति |  (Aranya Kanda 12th Sarga 17 - 21 Slokas)

Sri Rama entered inside the hermitage and saw therein the sanctus of Brahma, Fire-god, Vishnu, Indra, Vivasvat - the Sun-god, Soma - the Moon-god, Bhaga - one among the twelve Suns, and the sanctusms of Kubera, [Wealth-Management-god, are seen and passed by the three of them, sanctums of Dhaata, Vidhaata - Vedic deities created by Brahma to help Svayambhuu Manu, santucm of Vaayu - the Air-god, and also like that the sanctum of great-soloed VaruNa - the Rain-god who also wields noose, and the sanctum of Gayatri - the presiding deity of gnosis, sanctum of Vasus - eight of them, and the sanctum of cobra's king - aadi sheSa, the divine Thousand-headed serpent that bears this globe on its head,  and even the sanctum of GaruDa - the Divine Eagle , and the half brother of aadi sheSa, and the sanctum of Kaartikeya - chief of gods army,  and the sanctum of Dharma - Dharmaraaja, presiding deity of Virtue-Vice-Time of living beings, in-charge of the hell.

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2.  Similarly, Incarnations or Avatars of Lord Vishnu did not find place in Srimad Ramayana.  The story of Nrisimha, the avatar might have been evolved based on Vedic story of Killing of Namuchi by Indra.  Namuchi got assurance by Indra that he will not kill him with a weapon in day light or in night. Later Indra killed him at the twilight time with the help of foam.

3.  Similarly, Lord Ganesha story might have been taken from the story of Sri Hanuma. 

4.   Sri Hanuma was hit by Indra with thunderbolt.  Enraged with that act his father Vayuu withholds his energy from the world thereby causing panic.  Indra and other gods pacify Vayuu and give boons to Sri Hanuma.  Lord Brahma gives Sri Hanuma a boon that no weapon including that of all powerful Bramhastra could harm him.  Lord Indra gives him the boon of 'ICCHA MARANA", i.e., death will come to him at his will, as Bhishma got in Mahabharata.

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Jambavanta narrates the story of Sri Hanuma as follows:

अभ्युत्थितम् ततः सूर्यम् बालो दृष्ट्वा महा वने |
फलंचेतिजिघृक्षुस्त्वमुत्प्लुत्याभ्युत्पतोदिवम् - यद्वा -
फलम् च इति जिघृक्षुः त्वम् उत्प्लुत्य अभिउत्पतो दिवम् || (Kishkinda Kanda 66 Sarga 21 Sloka)

"Thereafter, when you were a boy you have see the just risen sun in the vast of forest, and deeming it to be a just ripen reddish fruit, and thinking it to be a best catch, you hopped up and flew towards sun on the sky.."

शतानि त्रीणि गत्वा अथ योजनानाम् महाकपे |
तेजसा तस्य निर्धूतो न विषादम् ततो गतः ||  (Kishkinda Kanda 66 Sarga 22 Sloka)

"Even on your flying up three hundred yojana-s, oh, brave monkey, and even when sun's radiation puffed and blown you down, you did not get into any anguish as were indefatigable."

त्वाम् अपि उपगतम् तूर्णम् अंतरीक्षम् महाकपे |
क्षिप्तम् इन्द्रेण ते वज्रम् कोप आविष्टेन तेजसा ||  (Kishkinda Kanda 66 Sarga 23 Sloka)

"Oh, mighty monkey, even on seeing you who are coming near the vault of heaven, Indra is captivated by anger and by his effulgence he catapulted his Thunderbolt at you..."

प्रसादिते च पवने ब्रह्मा तुभ्यम् वरम् ददौ |
अशस्त्र वध्यताम् तात समरे सत्य विक्रम || (Kishkinda Kanda 66 Sarga 27 Sloka)

"Oh, chivalric warrior at war, while the Air-god is being supplicated, oh, dear boy, Brahma gave you a boon decreeing your 'indestructibility by any missile..."

वज्रस्य च निपातेन विरुजम् त्वाम् समीक्ष्य च |
सहस्र नेत्रः प्रीत आत्मा ददौ ते वरम् उत्तमम् || 
स्वच्छंदतः च मरणम् तव स्यात् इति वै प्रभो |  (Kishkinda Kanda 66 Sarga 28 Sloka)

"On scrutinising that you are unhurt even after hit by Thunderbolt, oh, ablest Hanuma, the Thousand-eyed Indra kind-heartedly gave you a choicest boon saying that your death occurs only by your own volition..."

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4.  In Lord Ganesha story Lord Shiva beheads Ganesha with his TRISHULA and Goddess Uma gets enraged.  Lord Shiva and other gods try to pacify her and give life to him by placing a elephant head and give boons to him

5.  Srimad Ramayana was written at the end of Vedic period and much much before Mahabharata and Puranas were written.  The age of Srimad Ramayana could not be established with authority.