The Gods have been supposed to rule prior to the descent of man. When a man showed up on the earth it is believed the Gods have already left the firmament. But this doesn’t explain why Brahma, the God of creation in Hindu mythology faded away into obscurity? The laws of Manu grace the stature of Brahma though, in modern and recent times, Brahma has taken a backseat while more festivity is bestowed upon Lord Shiva.
As according to Puranas it was Vishnu who first appeared then the Brahma was born who proceeded with the creation. So Brahma is somewhat relegated to Vishnu in stature and thus Brahma has been ignored by the worshippers. Moreover there is a story that goes a certain Rishi put on some questions to Brhama who didn’t respond and in turn, the Rishi cursed Brahma that in present-day Kalyuga no one would worship him.