I personally think they are simply different. Can't see a superiority vs inferiority relation outside a perspective of personal taste.
Some people prefer Bughouse over standard Chess, so one could say Bughouse is superior for them. You prefer Chess over all other Variants, so you say Chess is superior for you. In the end there is not one single irrefutable statement.
Now one could say that those other forms are less popular. In this case it'd be accurate, as we all know that standard Chess is the most popular Chess form there is.
It seems like all the forms of chess available in the community championships are the make believe chess categories:
Chess960
Spell Chess
Bughouse
Duck
Fog of War
Seirawan
Crazyhouse
None of those really matter. Even Hyper Bullet is kinda cringe b/c its just blunder chess
And why can't there be different versions of chess ?
Chsss is not the one true version of chess before he modern version there was cachagura or something (I don't know how you say it ) things evolve overtime most likely once computers solve chess chess960 will before more popular for competitive players