Shareholders are the public, it's a public company.
[1] https://finance.yahoo.com/news/the-richest-1-own-50-of-stock...
Yes, they are a subset of the broader public, but it's unlikely they are a representative sample of the whole. In fact, being shareholders immediately bakes a bias into their thoughts and actions. That bias alone separates them from The Public.
Yes, they are members of the public. No, they are not synonymous with The Public.