In a very real sense, imperative programming _is_ natural. Its much closer to how computers work. Whether this means that its an easier way to learn is up for debate. (For the record, I think it is easier for a majority of people, but that functional would be easier for a significant minority.) Your phrasing of that part just kind of bothered me.
I think we already teach beginners that you calculate the sum of the squares of a list of numbers with a for loop. Actually, its a fairly common type of problem when you're learning about for loops. Maybe I'm missing your point?
Natural != how the machine works. Few of us have the faintest clue about how the laws of thermodynamics apply to the internal combustion engine or how solid state physics leads to semiconductors leads to electronics leads to electronic injection. Yet we all drive cars as naturally as we walk.
I'd argue that your analogy strengthens my point. In their original form, cars involved people manipulating the mechanical parts as directly as possible (the steering wheel was completely tied to the front axle, the gas pedal, brake, starting crank all directly controlled a single aspect). And yet, we drive cars so naturally. I think using the word natural in this sense makes a lot of sense.
I think we already teach beginners that you calculate the sum of the squares of a list of numbers with a for loop. Actually, its a fairly common type of problem when you're learning about for loops. Maybe I'm missing your point?