What advantage did the Congress party have over other political parties in the first few General elections of India?

It had a broader social and ideological coalition.

This first phase of democratic politics in India was unique due to the inclusive nature of the national movement led by the Congress. It attracted different sections, groups, and interests, forming a broad-based social and ideological coalition. The Congress's key role in the freedom struggle gave it an advantage over others. However, as Congress's ability to accommodate diverse interests and aspirants for political power diminished, other political parties gained greater significance. Thus, Congress's dominance was just one phase in the country's politics.