Only the 21 original heroes

Well yeah, that’s what “Classic” means.

As I said months ago:

And logically, they have gone with a May 2016 version - because that’s what “Classic” actually means. But classic also means disabling half of the game’s heroes - and that is something I don’t think a lot of people actually want long-term. And it also means bringing back a bunch of game mechanics that people really didn’t like.