Hinduism believes in the concept of Brahman – the Supreme Being which is present in all animate and inanimate objects. Therefore it is not founded by any human being or prophet. It is also not an organized religion and therefor it has no founder.
Hinduism is based on universal truth and it applies in humans, animals and non-living everywhere. This universal truth was realized by the great Rishis or seers. Perhaps by a single Rishi or by several Rishis in several places. The Rishis were not confined to any age or place.
What they realized was that there is nothing outside the creator - in simple terms the creator is present in everything. The numerous gods and goddesses in Hinduism are representation of that eternal truth.
The great lineage of the Rishis continues and I and you all are part of it. But we need to realize it.
Interestingly, the word 'Hinduism’ does not appear anywhere in Hindu scriptures. The true name for Hinduism is ‘Sanatana Dharma’ and Sanatana means ‘eternal.’ There is no apt English word for ‘Dharma’ and the nearest explanation is duty or code of life. Thus Sanatana Dharma means ‘eternal law.’
It must be noted that Sanatana Dharma does not believe in the concept of religion. Religion destroys universal truth and creates compartments. For Sanatana Dharma, Buddha, Mahavira, Prophet Mohammed, Jesus Christ, Lord Krishna are all part of the great lineage of Rishis who are self realized and have taught the Truth.
Although Hinduism is considered to be the oldest religion in the world, the term Hinduism was coined much later. The word ‘Hindu’ by Arabs and ‘Hinduism’ much later by Europeans.
Finally, one who has realized Brahman will never bother about religion or founder or beginning or end.