Here are some simple, nice Jain baby boy names starting with the letter D along with their basic meanings:

1. Darshan – Spiritual vision, right perception of truth.
2. Deepak / Dipak – Lamp, that which gives light (symbol of knowledge).
3. Devansh – Part of the divine, portion of a deva.
4. Dhruv – Steady, firm, unshakable (also a famous devotee in Jain stories in some traditions).
5. Dheer / Dhairya – Patience, calmness, courage.
6. Divyam – Divine, pure, full of light.
7. Dinesh – Lord of the day (sun), often used in religious families.
8. Dhiren – One who is steadfast and patient.
9. Dipesh – Lord of light, connected with inner light of knowledge.
10. Devendra – King of devas (often used as a respectful, auspicious name).

More specifically Jain-leaning names (heard often in Jain families):

1. Dharamraj / Dharmaraj – King of dharma (righteousness).
2. Dharmesh / Dharmes – Lord of dharma.
3. Dharan – One who upholds, supports (dharan: to hold).
4. Devkumar – Noble / divine son.
5. Dwijendra / Dwijesh – Related to “twice-born” (spiritually awakened).

If you tell me your community (Digambar / Shwetambar, or language like Hindi/Marwari/Gujarati), I can suggest more names that fit that style and are clearly Jain in tone.