Short answer: No.

In Jainism, a Tirthankar is not an incarnation (avatar) of a God. A Tirthankar is a human soul who, after countless births and the fruition of Tirthankar‑nāma‑karma, is born with extraordinary spiritual capacity, attains Keval‑jnān (omniscience), establishes the fourfold saṅgha, shows the path to liberation, and finally becomes a Siddha. There is no creator‑God who “descends” as avatars in Jain philosophy.

• Every soul takes rebirth due to karma. A Tirthankar is simply a perfectly purified soul in its final human birth, not a divine descent.
• There are 24 Tirthankars in each half‑cycle of time; the last of our era was Bhagwan Mahavira, who attained moksha and does not return.
• Example from tradition: the soul that became Mahavira had previous births (e.g., Marichi). This shows karmic continuity, not incarnation of a deity.

Digambar and Shwetambar traditions both agree that Tirthankars are enlightened human beings, not avatars. They differ slightly in some life‑details and dates, not in this core principle.

For a simple overview: On “what is a Tirthankar”: On Mahavira’s previous births (e.g., Marichi):