Considering how Venti, Bennett, Kazuha, Xiao, Raiden, Xiangling, Diluc, Childe, Eula are more used than ganyu and clear abyss faster, it is hardly surprising that another unit like Shenhe will be better than ganyu. Itto will probably be better than ganyu too.
The OP units Xiao, Venti, Kazuha set the bar too high. There's no way for ganyu to compete at all. She's nowhere near bennett level even.
As a mixed being, ganyu is torn between dps and support but fails at both categories. A pathetic existence if you ask me. Rosalyn (Signora) was also a deluded mixed being wielding cryo and pyro forms, and we all know what happened to her: she got the execution she deserved.
Ganyu has absolutely no niche, does not work well with anybody, and her c6 is unusable anywhere. That added to a crap weapon, no bis artifact set, inferior base stats, and having no synergies whatsoever, ganyu is truly the lowest of the low and a complete dud of a character, worse than kokomi, klee, and keqing. No idea why this peasant of a character was ever released.
Even after ganyu trained with her master Xiao, she still apparently has not learned her lesson or how to even be a viable dps.
Tbf, what's the point in using ganyu when Kaeya, Eula, Rosaria, Chongyun exist
These are the most used units in the last version 2.2 Spiral Abyss among those who completed it:
Bennett (99.01%)
Venti (98.73%)
Xiao (97.66%)
Kazuha (97.62%)
Raiden Shogun (97.54%)
Diluc (95.15%)
Mona (95.02%)
Tartaglia (93.64%)
Xingqiu (89.79%)
Hu Tao (84.44%)
This is based on a sample size of at least 100 thousand users.
