Linux Mint lists 11 people in their GitHub org. There's likely additional outside contributors, but that's the core team. In the Cinnamon repo, only 5 people have changed more than 1000 lines of code in the last two years.
I expect CentOS to have even less contributors, as they largely just repackage what Fedora does.

Mozilla has around 750 employees, most of which are fulltime devs.
Like, man, I don't want to kill your optimism, but we're talking an order of magnitude difference at least.