As indicated above, the Tour-de-Zwift rides are categorized based on length of the event and not level of riders.
Even "winning" the shorter events will require some real efforts from strong riders.
Regarding your cat. To me it actually seems you're a strong B-rider (top of cat wrt FTP)
jumping to A is possible for flat races I guess however be prepared to dig deep in anything remotely hilly (you propably need to be able to do > 5.5Wkg for 5min to just stay with the lead group on shorter climbs)
Even "winning" the shorter events will require some real efforts from strong riders.
Regarding your cat. To me it actually seems you're a strong B-rider (top of cat wrt FTP)
jumping to A is possible for flat races I guess however be prepared to dig deep in anything remotely hilly (you propably need to be able to do > 5.5Wkg for 5min to just stay with the lead group on shorter climbs)