Here are some good Jain-friendly boy names starting with D, with simple meanings:

1. Darshan – दर्शन – spiritual vision, seeing the truth
2. Dhruv – ध्रुव – firm, steady, a bright star; symbol of steadfast devotion
3. Divyam – दिव्यम् – divine, full of light
4. Dikshant – दीक्षांत – one who has taken (or is close to) spiritual initiation
5. Devansh – देवांश – part of the divine
6. Devendra – देवेंद्र – lord of gods; respected, noble person
7. Dhanush – धनुष – bow; symbol of focus and aim
8. Devit / Devit – देवित – godly, divine nature
9. Deval – देवल – holy place, temple
10. Dharmil – धर्मिल – one who follows dharma (righteousness, moral path)
11. Dharmik – धार्मिक – religious, righteous
12. Dharan – धरण – one who upholds; stable and patient
13. Divesh – दिवेश – lord of brilliance/light
14. Dhiraj – धीरज – patience, endurance
15. Dipesh / Deepesh – दीपेश – lord of lamps/light; one who spreads light

If you tell me what kind of name you prefer (very traditional, modern, very short, based on a Tirthankar, etc.), I can suggest more focused options.