As written in the title I want to know that what are Trideva(Brahma, Vishnu, Shiva)- Creator or corporeal of God(only). Many people say that Trideva are creator themselves and other say that they are only corporeal of God. For that I am quite confused. I think they are only corporeal of god like other Devas. What do you think about it?
In the beginning, there was nothing in the universe. There was only darkness and the divine essence (brahman). It is impossible to describe the brahman, it has no traits that can be described. When the time came for creation to start, the brahman removed the darkness and divided itself into three. These three parts came to be known as Brahma, Vishnu and Shiva. The first object that was created was water and Vishnu slept on this water. Since nara means water and ayana means resting-place, Vishnu is accordingly also known as Narayana. In this water next appeared a golden (hiranya) egg (anda). The egg shone with the radiance of a thousand suns. Inside the egg, Brahma created himself. Since he effectively created (bhuva) himself (svayam), Brahma is also known as Svayambhuva. The egg, you will remember, was golden. Garbha means womb, and since Brahma was born inside a golden egg, he is also known as Hiranyagarbha. For a thousand years Brahma stayed inside the egg. He then split the shell into two and emerged out. Heaven (svarga) was made from one half of the shell and the earth from the remaining half. All the land masses, the oceans, the rivers and the mountains, had been inside the egg in embryonic form. Brahma made them manifest.
same is asserted in vayu purana and kurma purana too.
As per Srimad Bhagavad Mahapurana "In the beginning, there was nothing in the universe. There was only darkness. In the immense void if one looks closely into the depths, at the bottom of the dark ocean, Lord Vishnu is asleep on Sesha Naga. As the time for creation arises, the Lord awakens - in this Kalpa, from his navel sprouts a divine lotus on which is seated the Creator Brahma. He looks around to see what is their and as he looks around four heads of his sprout up one facing each direction. and as per Vishnu's instructions, Brahma begins the job of creation. As creation progresses Vishnu sees the growth of undesirable qualities and hence to maintain the balance He takes yet another form of the Destroyer Shiva."
Therefore the Trideva are Swayambhu i.e. self created and not born of any parents.