No, he was not the 1st BuddhaAnswer:Siddhartha Gautama is regarded as the initiator of Buddhism, not Hinduism.
The life of Sidhartha Gautama, the Buddha
Siddartha Gautama is the real name of Buddha. He was commonly known as Buddha because he created the belief of Buddhism. But his real name is Siddartha Gautama.
It all started with shakyamuni aka sidhartha Gautama who was the first Buddha born in India.
Hinduism
"Buddha" means "Awakened One". Sidhartha Gautama became known as The Buddha after his awakening.
During Siddhartha Gautama's lifetime a form of Brahmanism which lead to Hinduism, based upon the Vedic religion was the predominate religion.
Some Hindus consider Gautama Buddha to be reincarnation of Lord Vishnu.
Hinduism developed into Buddhism from the teachings of Siddhartha Gautama, who is better known as the Buddha.
Hinduism existed many years before the birth of the Buddha.
That is how I see it too since Gautama Buddha was a Hindu prince. The teachings in Buddhism is parallel to the Hinduism.
Mrs Sidhartha Mallya