From a Jain point of view, the answer has two parts: 1) what Jain scriptures/tradition say, and 2) what historians say.

1. According to Jain Dharma

• Jainism is described as anādi–ananta dharma – beginningless and endless.
• It does not “start” with any one person (not even Mahavira). Tirthankars like Rishabhdev, Parshvanath and Mahavira are revealers and revivers of an eternal path, not founders of a new religion.
• So in Jain understanding, you cannot really say “older” or “younger” than Hinduism, because Jain dharma is seen as timeless.

2. According to history / modern scholarship

If we talk in normal historical terms (dates, texts, archaeology):

• The oldest known Hindu/Vedic texts, like parts of the Rig Veda, are generally dated earlier than the historical life of Mahavira (24th Tirthankar).
• Mahavira is placed around the 6th century BCE (exact dates differ slightly between Śvetāmbara and Digambar traditions).
• So, from a purely historical-text viewpoint, the Vedic/Hindu tradition is older than Mahavira’s time.

However:

• Jainism clearly already existed before Mahavira – for example under Parshvanath (23rd Tirthankar), about ~250 years earlier, and Jain tradition traces itself back through many Tirthankars and cycles of time.
• So historians see Jainism as one of the very ancient Indian traditions, developing alongside the Vedic/Hindu currents, not as something new or recent.

Simple summary

• Jain tradition: Jainism is eternal; it does not begin after Hinduism and is not born out of Hinduism.
• History textbooks: Early Hindu/Vedic scriptures are older than the historical figure of Mahavira, but Jainism itself is also extremely ancient and independent.

If you want to read more on this topic in simple language, you can see this discussion on JainKnowledge and also here .