At that time I answered to this same question. I said, ‘You make samosa, kachori, parantha. Different types of food are all made with wheat. Why?’
There is phulka, roti, parantha, noodles, all are also made with wheat. The same wheat is used in many different ways.
Similarly, God has also not produced one vegetable for you, otherwise lifelong you would have to only eat brinjal, He has done that. How many different types of vegetables are created for you?
The creator who has created so many varieties, would He not like to manifest Himself in different forms and colors? We also say one God, but there are many forms, many names - Ananta Gunamaye, Ananta Naami. In thousands of names, thousands of qualities there is only one Paramatma.
Humans have known this fact. Knowing this, they became very happy.