India's financial inclusion transformation between 2014 and 2024 — driven by the JAM (Jan Dhan-Aadhaar-Mobile) trinity, the Unified Payments Interface's democratisation of digital payments, and the proliferation of mobile-based credit, insurance, and investment products from fintech companies — constitutes one of the most rapid financial system transformations in economic history. The Jan Dhan Yojana opened 510 million bank accounts by March 2024; UPI processed 131.2 billion transactions valued at ₹199.9 lakh crore in FY2024; and the Account Aggregator framework is enabling data-based credit access for thin-file borrowers who were previously entirely excluded from formal credit. This transformation has occurred at dramatically uneven pace across India's geographic and demographic landscape, creating natural variation in fintech exposure that can be exploited for causal impact identification. This study examines the effects of fintech adoption on financial inclusion depth (savings behaviour, credit access, insurance coverage, investment participation) and financial wellbeing across 4,280 rural households in Rajasthan, Bihar, Odisha, and Tamil Nadu, using difference-in-differences exploiting the differential rollout of Aadhaar-linked payment infrastructure across districts. Mobile financial services adoption rates range from 6.8% (Odisha rural) to 72.4% (Tamil Nadu rural) in 2024, having risen from near-zero baselines in 2019 — a differential that reflects infrastructure (internet connectivity, smartphone penetration), digital literacy, and supply-side fintech service availability. The World Bank collaboration contributes the Global Findex Database methodology for financial inclusion measurement that enables international comparison of India's rural fintech adoption impact.