It's usually either me and 2 other adults in charge of a bunch of Cub Scouts - when we bring a gas powered Burco for water and 4 gas rings for cooking (and occasionally a fire grate in case we get adventurous and properly "scouty"!).
Or else it's me and DD (who is now a proper Scout herself) so we have a 1 ring gas stove, a mini charcoal BBQ, and a Kelly kettle (and occasionally, if we can get into a Scout campsite, we have an actual fire grate to cook on).
The Kelly Kettle works well to both heat water and cook on top of with just a few sticks or pine cones.
The gas ring is perfect to heat enough water for an early morning cuppa, and works fine to cook for just 2 if you plan it right.
The BBQ is roughly 12" diameter, from Aldi a few years back, and is big enough to cook for 2 or 3, and I usually throw the kettle on top while it starts and once we've finished cooking to get hot water for tea and washing up. (And then fill a flask with any leftover hot water for later). You don't just have to do steak or sausages on a BBQ - skewers can do all sorts including mixed veg, and by wrapping things in foil, you increase your versatility hugely as well (packets of mushrooms cooked with salt, pepper, thyme and butter; a mix of the same sized dice of carrots, potato, sliced onions and some salmon chunks; mixed mediteranean veggies in the same sized chunks, etc). Or you could put a pot or pan on top and just use it like a "normal" cooker/heat source.
Google "backwoods cooking" for some ideas.
Our "girls adventure" trips (started when DD was 9) tend to do things like:
Breakfast
Tea or coffee (DD now drinks a lot of tea, I always need coffee to function and have a plastic plunger pot for camping!) so boiled water
Often pancakes - I bring a ziploc bag with the main mix already in it(flour, pinch salt, some baking powder/bread soda, little bit of sugar) and just add the milk (and an egg), close the Ziploc again and shake well/"smush" together until it's mixed, carefully pour onto hot pan. A clean and washed out 1l milk bottle would also work well for this (a plastic or tetrapak type with a lid to screw back on to allow vigorous shaking).
Or cereal/yoghurt/berries/bread and jam etc. Maybe croissants if we bought them the previous day.
Occasionally bacon.
Occasionally French toast/eggy bread on a pan - just plain egg, I don't tend to bring things like vanilla although it might be nice
Occasionally a fried egg with some fresh bread to dip (I never tend to get the fire going for morning toast, I rely on gas for the hot water then)
Lunch:
Usually cold - sandwiches, salad, etc.
Maybe tea or hot chocolate if necessary to warm up.
I usually have a soup with me in case of bad weather and needing heating/cheering up.
Dinner -
Sometimes a crispy French stick cut into chunks, and hot rotisserie chicken from a deli en route back to site, and some salad to make our own sambos.
Tin foil parcels - we love the salmon version above
BBQ and salad and baked baby potatoes (wrapped in foil and chucked into the BBQ coals - baby ones work ok sizewise)
Chilli or fajitas or tacos meat mix served into wraps or tortilla "baskets" or spooned into the open side of a bag of dorito chips, grated cheese, sour cream and tomatoes available to let people personalize them
I've been known to bring a spag bol or a curry sauce from home to reheat and just cook pasta/rice - but that feels like cheating to us (we're only away a couple of days and always have loads of ideas to try - but it's handy for set up day), or a jar of sauce and some raw meat another night could be an easy night if you need it (I always have the makings of that on self catering hols, just in case)
Cook sausages on sticks over a fire/bbq and serve in hot dog buns or crispy rolls
BBQ can change between steak, chops, sausages, chicken, ribs, fish, prawns, use different marinades....so even relying on a BBQ doesn't need to be boring.
I find I use a lot of tin foil and Ziploc bags as part of my camping and self catering kitchens - for prepping, mixing, storing....and easy to bring with me or buy on arrival in most places
I would try to mix it up a bit - things you know they love but call them an outdoorsy name ("Cowboy Chilli" as the chilli over doritos, "Mountain Stew" for a stew type meal, "Explorers Eggs" for a plain fried egg, "Campers Delight" could be anything !!), and a few things they might find adventurous and try as part of the camping adventure.
And a small amount of a few different spices, seasonings, marinades, sauces etc could make all the difference - so chicken with sweet chilli sauce is very different to chicken with lemon and herb seasoning even though almost the same start. Do some plain if they might be slow to try new things (so cook most chicken as your chosen option, but keep a couple of chunks or 1 whole breast plain just in case you need it).
And having a chippie tea in a campsite, or using the local facilities (a pizza truck on the site, the local Chinese takeaway, or grabbing something ready to eat from a local shop/deli in late afternoon) are all part of a "proper" camping adventure.