Basic supplies:
bedding - you can go sleeping bags or you can go actual bedding. If you will be camping without hookups, add at least one extra cold weather blanket to your normal bedding practices; pillows; throw blanket for sitting areas if normally used.
Linens - wash cloth, hand towel, bath towel for each person (unless you normally share at home); dish cloth, dish towel; pot holder; beach towels (if going to water); a couple old towels/rags for emergency clean up, etc.
Tableware - whether disposable or real: dishes, bowls, silverware, mugs, cups (what size do you normally use at home - for me, I skip the middle size and get the large iced tea size and the small juice cups).
Cookware - fry pan that will fit for your family; pot that will fit for your family; spatula, turner, slotted spoon, etc.; can opener, bottle opener, knives, serving utensils if normally used.
Bathroom - your basic travel toiletry kit; first aid kit; ACE bandage, rubbing alcohol, hydrogen peroxide, tweezers (or tick tweezers), package of needles (for splinter removal), q-tips, toilet paper, bug repellent, aloe vera lotion, sunscreen, normal hygiene products used.
Miscellaneous - safety pins, scissors, tape (duct, electric, scotch), pens, pad of paper, flashlights/lanterns/headlamps, WD-40, can of air, basic tools (wrenches, hammer, screwdrivers, tape measure, etc.), extra batteries for flashlights, etc.; camp chairs, camp table.
RV specific items: 30-15 amp dogbone; 50-30 amp dogbone (if your RV is 50 amps), extension cord for your power (30 amp or 50 amp), stinky slinky, fresh water hose, power surge protector, water thief, chocks, leveling blocks/wood/etc.
Go basic to start - it's easy to add items as needed. If you can do an overnight test in your driveway, that's a great way to start. Spend 24 hours IN the RV - what did you reach for that wasn't there, those are the things you should consider adding. As you may have notice "if normally used" is really the kicker. Don't worry about having every single item "just in case". Get those items you normally use loaded.
As for meals, start with your simple favorite meals. Those that require the least amount of specialty ingredients and/or cookware/utensils. As you get comfortable with cooking in the RV, then you can expand and get more creative. Getting some shelf stable staples is always a good idea: canned soup, canned chili, etc. If something goes wrong with a meal or you wear yourselves out and don't want to cook, you can always hit this staple stash for a quick meal.
The above is a basic idea of the stuff you'll need. Depending on how you'll use the RV, these items could differ. Bring the basics to start, then add as you find you need things. Don't go overboard on trying to cover every situation, ask yourself: If I don't have this item, will it ruin the trip or just be inconvenient? If it will ruin the trip, bring it; if it is just inconvenient, then consider how much. For me, I find I'm OK doing things the old fashioned way and not bring as much stuff.
And, most important, each year, do a "Use Study" of the stuff in your RV. If you didn't use it in the past year and it is a "convenience" item (versus an "it will ruin the trip" item), then eliminate it. Don't fill up with stuff you don't use.
As someone who doesn't like eating the same thing every day, I would never make a giant pot of chili and freeze it for the trips. Those containers would just fill up precious space. So, if you like cooking in bulk like that, then do it - but if it's not your thing, don't force yourself.
The last thing is to simply look at what you use at home on a daily basis - those are the items you want to make sure you have. Those specialty items that get used once every few weeks or months don't worry about.
