Yeah, unfortunately you get the zenith hull from the hell that is three way war (Shattered pillar vs dark spire and neinzul astrid).
At the frigate level, there is no difference between the Human and Zenith hulls. At the destroyer level, the difference is pretty small, although it depends a bit on which modules you use. 10%-ish for base modules, reversed if you have DAs but not Polarizers. Only when you start to get into the Cruiser or Battleship level do the differences really begin to matter.
The Zenith shadow frigate hull (and the Spire shadow frigate hull, for that matter) does 360kdps against starbases. The Human shadow frigate hull does only 150kdps. They can each mount one or two missile launchers, which each do 150kdps/mark against starbases. (Spire Plasma Siege Cannons do 100kdps/mark against starbases and heavy ships, but the zenith is frankly just plain the best hull out there for nebulas).
I was thinking of the modules, but yeah, for Nebulas the Zenith hull has a better DPS main weapon over the Human hull's multi-shot and Light-group multipliers.
Spire Plasma Siege modules, though... Yeah, they work against heavy ships, which missiles don't. But killing starbases and other Ultra-Heavies, which is how to win 7 of 9 scenarios, is more important.
I don't think any frigate can reasonably kill a large starbase anyway. Every starbase has a bonus against you, and your hull doesn't have a bonus against it.
It takes a couple of runs, but it can happen.
At frigate level, assuming Mk II modules, 1 shield module, 1 missile module, and all small as either DA or polarizer, the Zenith hull does roughly 990,000 DPS on average. The Human hull does roughly 770,000 DPS on average.
Large starbases have around 100,000,000 HP (90M for Neinzul, 120M for Zenith) and do about between 1,500,000 DPS (Spire) and 3,000,000 DPS (Sorrow's Fang).
It'll take 2-3 runs, but you can do it.
Depends on how long your shields hold up but either way, how much DPS do they manage?
Bombers? Bombers are steady-state at 12 active units, and at Mk I each does 2880 DPS plus a 6x multiplier vs Starbases. That's a total of 207,360 DPS per Bomber Bay per Mark.
Unfortunately, drones have issues. First, as Aquohn said, is that with no HP, they die like flies. Heavy ships and starbases kill your entire spawn without any noticable delay. Second, and almost as importantly, drones do not inherit the targetting info of the parent Champion. This means they are likely to shoot at something - anything - except the starbase. Finally, range and targeting issues cause firing delays, which reduces the number of shots fired by the drones during their lifespan and thus DPS.