That cover is based on the favorite characters for current ongoing authors. So, they most likely select more than one characters in order to not being overlap with others.
--- Update From New Post Merge ---
Here are the authors' comments for Issue 33 cover:
Hidden:
Also, here is more information about which authors choose which character:
- Tsukuda Yuuto (story author of Shokugeki no Souma) = Shindou Hikaru (from Hikaru no Go)
- Shirai Kaiu (story author of Yakusoku no Neverland) = Bruno Bucciarati (from Jojo's Bizarre Adventure)
- Inagaki Riichirou (story author of Dr. Stone) = Aida Nukesaku (from Tsuide ni Tonchinkan)
- Matsuki Tatsuya (story author of Act-Age) = Kojima Mizuiro (from Bleach)
--- Update From New Post Merge ---
Here are the special illustrations from Jump authors to celebrate Jump's 50th year anniversary:
Hidden: