How many characters are too many?

This story question usually arises when there are several or a dozen or so, considered to be main, characters.

Movies like Spartacus (1960) have hundreds of characters but only several main ones and only one hero.

It's a question of managing goals.

Your characters arc, so you'll have to consider how you'll show that for each character. You can create before and after worlds where they all show before and after states, for example.

You can group characters into opposing sides, for example, which reduces it to two entities (and maybe one in the middle, like Die Hard,1988).

You can have a group of characters assisting main characters, like Ocean's Eleven (2001).

It's all possible, it's just a question of managing goals effectively.

Read the 2000+ stage Hero's Journey/Transformation/New World, which you can purchase from http://www.clickok.co.uk/index4.html