I've tried this before, so let me tell you that
Hamlet Captain is a trap. Cast on curve it's just a bear. When attacking on T2 it will only buff OTHER humans, not itself. Meaning it needs to be cast after a 1-drop, probably
Kytheon, Hero of Akros or
Expedition Envoy, to give value. To make it a real threat you will then have to cast between 1 and 3 more humans on T3. Congrats, if one is another Captain or even a
Hanweir Garrison. All this time Captain has a giant target on his hairy 2-toughness bear butt.
So, to play the Captain in Naya you need at least:
1 x
Kytheon, Hero of Akros3 x
Expedition Envoy3 x
Hamlet Captain2 x
Hanweir GarrisonTo keep dropping threats for Captain to buff you will probably need 3 more 1-drops and all we have left are:
4 x
Akroan Jailer3 x
Anointer of Champions3 x
Inventor's Apprentice4 x
Crossroads Consecrator2 x
Oviya Pashiri, Sage LifecrafterSo,
Hamlet Captain pulls you towards Selesniya due to the number of playable human 1-drops, but the card you really want to play him with is
Hanweir Garrison.
In addition to this conundrum, the setup of the deck will force you into the mana mess you've mentioned: 14x White, 13x Green and 12x Red minimum.
Tl;Dr: Don't try Naya humans, and surely not with
Hamlet Captain. Naya Zoo might be viable, though, since you don't have to worry about creature types.