Growing up with RVs since I was 7 years old, and now I'm 64, it's hard to imagine someone brand new, who has no experience with an RV. Things I take for granted are tremendous obstetrical for someone who's never been down this road before. But in the end, it's really not all that complicated.
My parents travel trailer (1963) had a radiant gas heater in it. It took no electricity. Today's RV, pretty much all of them, use furnaces that depend on battery power to control the circuit board and the fan, and propane for the heat.
My parents trailer had a propane operated light affixed above the gas stove and was the only source of light in the camper. It ran off the propane tanks. Today's RV all run on 12 volt DC (battery) power, but stoves and ovens (for the most part) are still gas, unless you get a camper that's all electric. Lights are all 12 volt DC.
The older campers never had water heaters, today's do. Water heaters can run on both propane and electric, but still need that 12 volt DC battery to run the circuit board.
Older campers had 100 percent gas operated refrigerators and took no electricity at all. Times have changed. Today's RV have propane-electric refrigerators. Electric being 120 volt AC house hold current and will switch to propane when the power is off or disconnected. But they still take the 12 volt DC battery to run the circuit board.
Power awnings, electric tongue jacks, electric or hydraulic stabilizer jacks, outside lights, all, run on 12 volt battery power.
Today's campers come equipped with a 120 volt AC converter to 12 volt DC battery which charges the battery and also powers the 12 volt DC devices if you have no battery.
So, what I'm saying is, today's RV's, all ... have a 100% dependency on electricity in order to function. Where you get that electricity is the challenge.
If camping in an RV park or a campground, more than likely your campsite will have at least electricity. (unless you select a primitive site). But if you prefer to camp off grid (boondock) or primative, you'll need to provide your own electricity, either a generator or solar power. It's just that simple .... but not so simple to implement.
The days of truly "self-contained" RV is long gone. They have dependency's on electricity now. Boondockers take great strides to modify their RV to make them truly off-grid usable with solar and generators.