Is it because people realized their own limitations? Since there were so many things about the world that seemed unexplainable anyway?
On the other hand, the Hindus had a much more 'sophisticated' theory of creation (source):
In the Vedas
The Rig Veda describes the origin of the universe as:
"Then was not non-existence nor existence: there was no realm of air, no sky beyond it. What covered in, and where? and what gave shelter? Was water there, unfathomed depth of water? Death was not then, nor was there aught immortal: no sign was there, the day's and night's divider. That One Thing, breathless, breathed by its own nature: apart from it was nothing whatsoever. Darkness there was at first concealed in darkness this. All was indiscriminated chaos. All that existed then was void and form less: by the great power of Warmth was born that Unit. Thereafter rose Desire in the beginning, Desire, the primal seed and germ of Spirit. Sages who searched with their heart's thought discovered the existent's kinship in the non-existent. Transversely was their severing line extended: what was above it then, and what below it? There were begetters, there were mighty forces, free action here and energy up yonder. Who verily knows and who can here declare it, whence it was born and whence comes this creation? The devas are later than this world's production. Who knows then whence it first came into being? He, the first origin of this creation, whether he formed it all or did not form it, Whose eye controls this world in highest heaven, he verily knows it, or perhaps he knows not" - (Rig Veda 10.129.1-7)
But the Rig Veda's view of the cosmos also sees one true divine principle self-projecting as the divine word, Vaak, 'birthing' the cosmos that we know, from the monistic Hiranyagarbha or Golden Womb. The Hiranyagarbha is alternatively viewed as Brahma, the creator who was in turn created by God, or as God (Brahman) himself.
In The Puranas
The later puranic view asserts that the universe is created, destroyed, and re-created in an eternally repetitive series of cycles. In Hindu cosmology, a universe endures for about 4,320,000,000 years (one day of Brahma, the creator or kalpa) and is then destroyed by fire or water elements. At this point, Brahma rests for one night, just as long as the day. This process, named pralaya (Cataclysm), repeats for 100 Brahma years (311 trillion human years) that represents Brahma's lifespan. It must be noted that Brahma is the creator but not necessarily regarded as God in Hinduism. He is mostly regarded as a creation of God / Brahman.
We are currently believed to be in the 51st year of the present Brahma and so about 155 trillion years have elapsed since He was born as Brahma. After Brahma's "death", it is necessary that another 100 Brahma years pass until he is reborn and the whole creation begins anew. This process is repeated again and again, forever.