I have noticed that many aspects of hindu and Greek mythology are similar for example how all the gods originated from Earth goddess and sky god, how the god of sky is the ruler of all gods, and many more
I suspect that it is because of trade between India and Greece or maybe people of both countries shared same origin and split up Thier ideology into Greek and hindu mythology
In all likelihood, Greek and Hindu religious belief systems are similar not because of trade contacts, but because they are actually directly related, sisters descended from a prehistoric Indo-European religion or religious continuum. You can find further correspondences with Roman, Celtic, Germanic, Lithuanian, Slavic, and Hittite religions, all of which are also part of the Indo-European diaspora beginning roughly 6000 years ago and continuing in waves for another 3000-4000 years.
There are no direct attestations of these prehistoric Indo-European religious beliefs themselves, but like the proto-language, they have been reconstructed using comparative historical and linguistic methods. The basic framework will seem familiar: a chief daytime sky god (Indra, Zeus, Jupiter, Dei Patrous, and a few theologically demoted gods such as Tyr) whose daughter is the goddess of the dawn (Usas, Eos, Aurora, Eostre, Aušrinė). A pair of divine twins, usually the children of the daytime sky god (the Ashvins/Ashvieniai, Kastor/Castor and Polydeukes/Pollux, Hengis and Horsa, a possible Celtic cognate in Brân and Manawydan). Another pair of brothers involved in the creation of the universe or the foundation of the believing community (Manu and Yama, Mannus and Ymir, possibly also Romulus and Remus). A storm god (Perkunas, Perun, possibly Parjanya and Thor), a water god (Apam Napat, Neptunus, Nechtain) and a nature god (Pushan, Pan). A serpent (Vritra, Kaliya, Illuyanka, the Lernaean Hydra, Python, Jormungandr, Fafnir, Beowulf's dragon) slain, often by the thunder god.
Many, many other correspondences are disputed, debated or less certain due to insufficient evidence, and none of this is meant to discount other myths and beliefs that do arise out of cultural contact, but on the balance there's a wealth of evidence supporting a common origin for all of these Indo-European mythological/religious belief systems.