I know that Brahmins are very important in Hindu religion. Many rishis were Brahmins and some Gods were also Brahmins. Brahmins learnt the Vedas and taught the people. Does this mean Brahmins are the main people of Hindus?
Depends on what you mean by Brahmin. Ramakrishna Paramahamsa says (Gospel of Sri Ramakrishna, Chapter 6 The Master with the Brahmo Devotees, available here - http://www.belurmath.org/gospel/index.htm):
The conversation turned to the caste-system. Sri Ramakrishna said: "The caste-system can be removed by one means only, and that is the love of God. Lovers of God do not belong to any caste. The mind, body, and soul of a man become purified through divine love. Chaitanya and Nityananda scattered the name of Hari to everyone, including the pariah, and embraced them all. A brahmin without this love is no longer a brahmin. And a pariah with the love of God is no longer a pariah. Through bhakti an untouchable becomes pure and elevated."
Lovers of God are the main people of Hinduism.
I know that Brahmin do the religious works and some Gods and Rishis were also Brahmins like Brahma,Shiva,Parashurama,Vamana a Vishnu avatar. But Kshatriyas are also important because Lord Rama himself was a Kshatriya. Kshtriyas were the kings which we saw in some stories. We all are same that Lord Krishna had told to Arjuna. Actually,there is only one God. If we want to see that God in the form of Shiva,so the God will bless us in the form of Shiva,if we want to see that God in the form Vishnu,so that God will bless us in the form of Vishnu. Not Brahmins and Kshatriyas,we are all Hindus!!!
The word bramhin or bramhan has a very different meaning than that of what we choose to see in our caste system. This caste system is very old the meaning have been altered now, but the originally in sanskrit, "The one who can expand his mind" or thinker or Intelligent thinker is the bramhin. So by birth any and everybody is not a thinker, born in caste of bramhin does not really make him a bramhin but thinking all the perspectives or thinking in a beneficial way or on a higher level makes him a bramhin.
So does Kshatriya, means protector of people, in todays world you can say that, soliders/ police are kshatriyas because the protect people.
This original caste system was based on the work that they do and it does not depend in which family a person is born.
There are no Higher's or lowers to this system. For E.g. Bramhins, read books and gain knowledge and help kshatriyas to protect their cities, Vayshays as basically these are the businessmen's or tradesmen bring foreign money into the city. I hope this was clear. Apologies if I have represented it in wrong way. Being such a sensitive topic please forgive if any mistakes are made.