anything that was rationed
gas - all petroleum products actually
food meat dairy etc - sawdust for making bread was about the only thing not rationed in at least some parts of continental Europe at some point in time during the conflict.
rubber
tin
copper
uranium
steel - iron
aluminum
resources for making gunpowder and explosives - but might be commonly available.
rubber, oil, and steel were big players. you could almost say japan went to war over them.
as for what to call people and money - you're a general - so its not dollars. the country prints the money, gives it to the factories / workers, and they produce the output you need - IE war materiel. most wargames use the term "resource points".
people is just the available manpower for training. not the entire population can fight. some are too young or old, or not physically or mentally fit enough, some work in the factories, government, transportation sector, etc, keeping the home front chruning out war materiel and manpower.
so you'd have some amounts of material and manpower available to build buildings and train and equip units.
for an AOE type progression, you'd have military base as you basic recruiting building, perhaps port and airbase as well for naval and air units. at later "ages" you'd get better bases that could build better units like tanks vs inf, or build units faster, or multiple types at once, etc.
things like oils fields, iron mines, coal mines, and rubber plantations would be natural resources to fight over.
but like all RTSs, the model of iron+coal=steel steel+factory+materiel+ manpower=tank unit is unrealistically compressed in both time and space. never in ww2 did they ever capture a rubber plantation, then build a rubber factory next to it, then start turning out tires for trucks for infantry and arty which then took place in any nearby battle. they'd capture the resources, ship them thousands of miles off the game map, then have the units shipped back to the theater of action once produced. so unless your map covers the world , it'll be kind of weird. but it could be done - with proper scale of time and distance. but that would be a much more "strategic" game than your typical RTS. units would be divisions and armies and corps at the smallest. navies would be enitre fleets, air units would be entire sqadrons. kind of like third reich- that scale. the game map would be the entire world, say at about 250 to 500 miles per hex. contrast AOE where you have individual villiagers,or warcraft with orc grunts. one of the things about more modern war is its on a much bigger scale. its not a villager mining ore and a smiithy making swords and a training camp making individual warriors, its a mining complex with hundreds or thousands of workers. and factories with hundreds or thousands of workers, and buildings and units that take months or years to build. and things are hundreds or thousands of miles apart from each other. long build times and maps thousands of miles across are not typical material for an RTS type game. how does starcraft address that issue? i assume they have some sort of warp drive, so long distances are irrelevant. how long to build a big star cruiser? game years? it should be. but a battle involving one can be over in minutes. the differences in timescale between production and combat makes for a bit of a problem. i suspect this is more so with more modern techs which take longer to build.
the closest that ww2 came to rts production was the siege of stalingrad where cottage industry gunsmiths would assemble weapons which were immediately issued to troops in the city and saw action within hours of manufacture within blocks of their place of manufacture. but the resources were already there, shipped in from hundreds of miles to the east.
and sun and shadow is right - almost everybody saved and reused brass shell casings. except for us ugly americans, who were overpaid, oversexed, and over there.
manpower can win battles but without materiel you'll lose the war.
