How many developers are working on the Monero core platform? Is everyone anonymous?
There's a list here: https://getmonero.org/community/team/
2 of them made their identities known. Some of them are inactive. But the role of core team is not to do all the work. They're there simply as trusted gatekeepers of the project. I haven't seen them do much coding.
Coding is done by many other contributors. There are good stats on this here: https://www.openhub.net/p/monero