In Jain history, the major sectarian division is generally traced from Bhagwan Mahavira’s era, not from Lord Rishabhdev.

Why Mahavira and not Rishabhdev?

• Lord Rishabhdev is the first Tirthankar and the origin of Jain Dharma itself.
• But the recognized split into traditions/branches happened much later, after Bhagwan Mahavira’s nirvana.
• That is when differences in discipline, texts, monastic practice, and interpretation became visible and later formed the Digambar and Shwetambar traditions.

So the meaning is:

• Jain Dharma begins with Rishabhdev
• Sect division is associated with Mahavira’s post-nirvana period

That is why people say “division from Mahavira”, not “from Rishabhdev.”

In simple words:

• Rishabhdev = beginning of Jain tradition
• Mahavira = period when the later sect differences became established

If you want, I can also explain the historical reason for Digambar–Shwetambar difference in simple Jain terms.