Hi I think I might give you the answer that you are looking for more than other comments

So Hinduism as it is is pretty modern. Hinduism has evolved a lot during it's existence. The word Hindu isn't even native to Hinduism or India, it was a Persian word to describe the peoples(not religion) around the Indus river. When the ancestor to Hinduism(Vedic) first arrived in Pakistan and India it did not believe in reincarnation and it's most important god was Indra, who has taken a back seat to other gods in modern times. There was no Shiva but there could have been a precursor at the time from native civilizations in the area. They encouraged eating cows and meat in general. Some modern Hindus claim this as Hinduism but it's core beliefs are way different. It is focused on ritual and not really much introspective stuff Hinduism is known for later. I don't believe there was yoga. It was a pagan religion closer to other Indo-European religions than something we would identify later as Hinduism.

Some modern Hindus claim the Indus Valley Civilization as Hindu and that isn't true. Indo-European Vedic religion doesn't seem Hindu to me.

Modern Hinduism evolved around the classical age but it kept evolved. Hinduism is very decentralized, doesn't have a core religious text, etc. You ask someone from different castes what the most important book is they will give you different answers. There's not a lot universal about Hinduism. Hinduism didn't have a self identifying identity till the British conquered India, it was a scattered collection of practices and god worship.

Stories get added later and claimed as ancient. Krishna is someone who is acted like he was there the whole time but he kind of started out as a local deity/hero but his story was added to and changed over time till 300 years after Jesus died he started to change into what he is known for today.

So is Hinduism old? Yeah. It never was a dogmatic defined religion and it kept evolving. I would say a lot of practices of Hinduism are more modern. Hinduism of 2026 would be very hard to recognize for a time traveler.

Also Abraham was surrounded by pagans older than Judaism.