At the very least, you need to make sure that all the [RESPONSIBILITY] tags are accounted for. Copying the Dwarf Nobles will work for this (remember to rename positions like "Chief Medical Dwarf," though).
Note that this will drastically change the nature of human society as it is in the unmodded game. If you don't want to compromise this, you can still play a functional game with them in fortress mode, by copying/pasting the responsibilities from the various dwarf nobles into the one authoritative human noble position.
Like this:
[POSITION:WARLORD]
[NAME:warlord:warlords]
[SITE]
[NUMBER:1]
[MENIAL_WORK_EXEMPTION]
[RULES_FROM_LOCATION]
[SUCCESSION:BY_HEIR]
[RESPONSIBILITY:LAW_MAKING]
[RESPONSIBILITY:MILITARY_GOALS]
[RESPONSIBILITY:MILITARY_STRATEGY]
[RESPONSIBILITY:RECEIVE_DIPLOMATS]
[RESPONSIBILITY:LAW_ENFORCEMENT]
[RESPONSIBILITY:MEET_WORKERS]
[RESPONSIBILITY:MANAGE_PRODUCTION]
[RESPONSIBILITY:TRADE]
[RESPONSIBILITY:UPGRADE_SQUAD_EQUIPMENT]
[RESPONSIBILITY:EQUIPMENT_MANIFESTS]
[RESPONSIBILITY:SORT_AMMUNITION]
[RESPONSIBILITY:ACCOUNTING]
[RESPONSIBILITY:ESTABLISH_COLONY_TRADE_AGREEMENTS] <---Teal: Add these tokens
[RESPONSIBILITY:MAKE_INTRODUCTIONS]
[RESPONSIBILITY:MAKE_PEACE_AGREEMENTS]
[RESPONSIBILITY:MAKE_TOPIC_AGREEMENTS]
[RESPONSIBILITY:BUILD_MORALE]
[RESPONSIBILITY:COLLECT_TAXES]
[RESPONSIBILITY:EXECUTIONS]
[COMMANDER:WARRIOR:ALL]
[PRECEDENCE:10]
[FLASHES]
[BRAG_ON_KILL]
[CHAT_WORTHY]
[DO_NOT_CULL]
[KILL_QUEST]
[EXPORTED_IN_LEGENDS]
[COLOR:4:0:1]
[DUTY_BOUND]
And add [APPOINTED_BY:WARLORD] to the Warrior position.
Now you have a Warlord who rules everything with an iron fist, and all the Warriors you need to enforce said rule. You'll still have to add a doctor-type noble with [RESPONSIBILITY:HEALTH_MANAGEMENT] or you won't have a Health 'z' screen. For Dungeon Masters behavior, use [RESPONSIBILITY:TAME_EXOTICS].
Chances are, this warlord would
always be busy doing something. Question remains if you'll get a replacement Warlord when yours dies (if there is an heir present at the settlement you're playing, you may end up with a child in charge!). This is rather uncharted territory, so if you decide to do it, let us know the results. For SCIENCE!