I believe you are confusing a "creole" with a "pidgin".

https://en.wikipedia.org/wiki/Pidgin

> pidgin language, is a grammatically simplified means of communication that develops between two or more groups that do not have a language in common: typically, its vocabulary and grammar are limited and often drawn from several languages. It is most commonly employed in situations such as trade, or where both groups speak languages different from the language of the country in which they reside (but where there is no common language between the groups). Fundamentally, a pidgin is a simplified means of linguistic communication, as it is constructed impromptu, or by convention, between individuals or groups of people. A pidgin is not the native language of any speech community, but is instead learned as a second language

I'm not sure Mumbai Hindi would qualify as a pidgin either then since it's definitely the native language of a significant number of people.

Pidgins and Creoles are on a continuum -- once pidgin's get native speakers and a stable grammar, they're creoles. But Yeah, I didn't mention that.

Fair enough. Thanks for clarifying.