Of course, Hinduism is an India centric religion. It has undergone several changes during its evolution through the centuries of development. In the Vedic period the religion had a pantheon very similar to that of Greece and Rome. Indra, the King of gods and the god of sky, rain and thunder was similar to Zeus of Greece and Jupiter of Rome. Varuna had his counterparts in Poseidon(Greece) and Neptune(Rome). Surya was similar to Helios and Appolo. Chandra, though a male god had female counterparts in Luna and Diana. Kama had his image in Cupid while Rati was similar to Aphrodite or Venus. Thus almost all Vedic gods have their Greek or Roman counterparts. But in later years the Vedic gods, though they survived were pushed down in importance by the Thrimoorthi(Trinity) comprising Brahma, Vishnu and Shiva. Vishnu and Shiva were not prominent gods in the Vedic period. But a prototype of Shiva, in the form of Pasupati appears in the Indus Valley Civilization too. Shiva and Vishnu became the Supreme Gods of two groups of Hindus, the Shaivites and the Vaishnavites. These two groups had very strong rivalry between them and they fought each other as they also fought Buddhism and Jainism. It was the alliance of the two major cults, Shaivism and Vaishnavism that gave birth to the later Hinduism. Many other sects like Shakteya, merged into the union. The Trinity of Brahma, Vishnu and Shiva in charge of creation, preservation and destruction became the zenith of the pantheon. The Vedic gods became the servants of the top Three to obey and follow them. It is not clear when the Vedic period was replaced by the Puranic period or the Trinity became prominent. In the modern Hinduism there are no separation between the Shaivites, the Vaishnavites, the Shakteyas etc. But the devotees can choose their favorite god, Istadevata, to worship.
In Hinduism the philosophy, the mythology, the sects and forms of worship, the social organisation etc. are independent and the connections are weak. The philosophy consists of Sankhya, Nyaya, Yoga, Vaiseshika, Poorva Mimamsa and Uttara Mimamsa. These philosophic visions accept the supremacy of vedas and are counted as astika darsanas. The darsanas like Bouddha, Jaina and Lokayata which do not accept the authority of the vedas are considered nastika and out of the fold. Shankaracharya propagated Adwaitha, a strand of Uttara Mimamsa and through many debates and discussions established its supremacy. The vedic gods or Thrimoorthi do not come into philosophical debates and discussions.
The basic religious texts of Hinduism are the four vedas, Rig, Yajur, Sama and Atharva. Then there are six shastras, eighteen puranas, upanishads, aranyakas etc. etc. The two epics, Ramayana and Mahabharata are considered holy and Bhagavat Geeta is a part of Mahabharata. In the twentieth century Bhagavad Geeta grew in stature due to the attention of leaders like Bal Gangadhar Tilak and Mahatma Gandhi. Nowadays Geeta is considered as the most important religious text. The Hindu mythology grew from the epics and other books and is very large.
Then comes the social organisation and the caste system. The caste system which bring the followers of a particular profession together is very old. In the initial period the number of castes and the rigidity of the system was much lower. It must have been the arrival of Islam and later the Europeans that made the caste system very rigid. The coming of independence and the establishment of democracy have changed the nature and scope of the caste system. It has become an integral part of the vote bank politics and the political parties find it easy to manipulate the caste leaders and collect the votes of caste members in large groups.