Just for shiggles, let's ponder the title question.
Obviously human beings' needs for things like water and temperature are going to be pretty similar, and we already know which plants are compatible with regular human environments, because those are the plants we grow indoors, where we live, already. Therefore, we have to resort to metaphor for this.
So what I'm asking everybody to do (if you want) is, evaluate yourselves on a 0-3 scale, as described below, for each of the criteria, and then leave a comment, containing the numbers you come up with for yourself. I'll run your numbers through Excel, match them against the ratings for plants I've already got in the spreadsheet, and then post a list of the three plants with number sets most similar to the set you've given me.1 You may use any number between 0 and 3 (like, if you're just positive you're a 2.68 on something, the number 2.68 works as well as any other for calculating, so go ahead and tell me 2.68.). If you don't like my metaphors for which personality traits go with which plant-care categories, feel free to make up your own and give me those numbers instead.
PESTS are obviously other people.
0- People are great. I love meeting new people, and get along with everybody.
1- I like most people, though occasionally I run into someone I can't get along with.
2- I don't work or play well with others, but when I have to, I have to.
3- Other people are constantly getting in my way, being stupid, or otherwise causing me problems, and I wish I didn't have to deal with them.
Water is sort of raw material for doing anything, for plants. Basically "stuff." So for OVERWATERING, the question is how unsettled you are by having too much stuff, too much clutter, in your life.
0- I'm a hoarder.
1- I keep stuff a lot longer than I need to, and regularly buy stuff for which I have no immediate use.
2- Things occasionally get out of hand, but most of the time I keep my space fairly neat and organized.
3- I can't stand any kind of mess, even in space that doesn't belong to me.
And for UNDERWATERING, it's about how big of a problem it is for you not to have the things you need.
0- I can make anything I need from scratch using only duct tape and twigs, and sometimes I don't need the twigs.
1- I can usually improvise a bad substitute from something I already have, without having to buy something new.
2- I've been known to waste time going to multiple stores, trying to find something that will work perfectly.
3- I'll drop everything and drive for an hour to get exactly the right item.
LIGHT is basically energy input, for plants, which I think most closely parallels food consumption in humans. So
0- I'm basically anorexic.
1- I eat sensibly, most of the time.
2- I eat more than I ought to.
3- I eat anything that isn't nailed down.
For PROPAGATION, you have a choice: you can either treat it pretty literally, about your chances of having actual children, and the number of children, in your lifetime (0-I want to have a house full of kids / 1-definitely want some kids / 2-I might want one kid, someday / 3-I never want to have any children ever, or I can't have any childen ever), or you can be metaphorical:
0- I'm very proud of how much stuff I've accomplished in my life, compared to others my age.
1- There have been some unproductive spells, but I think on balance I've done quite a bit of cool stuff.
2- I could definitely have accomplished more if I'd worked harder, but considering what I had to work with I think I've done a couple worthwhile things.
3- I'm not sure I've ever done anything worthwhile in my life.
HUMIDITY . . . I'm going to say stress-management and ability to function under pressure, and/or ability to deal with frustration.
0- I deal exceptionally well with stress most of the time. Other people even compliment me on it and ask what my secret is. I'm thinking I should write a book.
1- I handle certain kinds of stress (like pushy co-workers or intense deadline pressure) very well, and other kinds (like disorganized workspace or lazy co-workers) not so much.
2- I work okay under moderate amounts of pressure, but fall apart when it goes on for a long time without a break/vacation or when I'm being asked to perform an exceptionally impossible task.
3- The slightest little thing will make me stress out to the point of being completely unable to function.
TEMPERATURE is a toughie, but I'm thinking it has to do with the intensity of daily activity, kinda. Since the meaning as it applies to plants has to do with the allowable range of temperatures, this is basically a measurement of how flexible you can be.
0- Whenever and however you want it, that's when I'll get it to you.
1- It's nice to have a little advance warning about things, but basically I can work at whatever speed is necessary without getting stressed about it.
2- I need to know pretty specifically what you want and how soon you want it, and depending on your deadlines I may or may not be able to get it to you.
3- I am no good with other people's deadlines. I have to work at my own pace, which is sometimes superfast and sometimes superslow, but I can't be rushed to do things faster, and I can't wait around for someone else's input once I'm ready to go.
GROOMING usually works out in the plant profiles as having special circumstances or quirks of care that aren't covered under one of the other categories but make the plant more difficult. So metaphorically, if your life is unusual in some way, compared to the average person in your country, because of who you are (disabled, gay, famous, independently wealthy, mentally ill), where you live (hippie commune, military, expat), or some other way that creates challenges for you that other people don't have or appreciate (self-employed, caring for a relative with special needs, religious minority, group marriage), this is where to note that.
0- I'm painfully ordinary in every possible way.
1- My life is a little weird.
2- I'm kind of a freak.
3- My life circumstances may be entirely unique in the history of the world.
FEEDING for plants is the input of trace elements, so for people I'm going to say it's about the need for novelty and stimulation, about how bored you get and how easily.
0- I'd be pretty happy to get on a routine that worked for me and stay in that routine until I die, with no changes at all.
1- Having a stable, routine life is definitely important to me, but it's nice to get away and do something different every once in a while.
2- I like to shake things up regularly, so I don't get into a rut.
3- I have to be doing something new constantly -- going new places, learning new things, trying new forms of physical activity -- or I get bored and cranky.
My personal numbers fall out as follows:
My closest match turns out to be Philodendron gloriosum.2 I'm the son of a Stromanthe sanguinea (Mom) and a Schefflera actinophylla (Dad),3 and I married a Philodendron 'Xanadu.' (So not only same-sex marriage, but same-metaphorical-genus marriage!)
The husband points out that there could be a financial opportunity in this, somewhere. Some kind of horti-horoscopes (Rhapis: your sharp tongue may get you in trouble with your boss today, unless you remember to think before you speak."), or personality tests, which could be sold to businesses or used in marriage counseling. ("Well, there's your problem: you're an Agave and he's a Dieffenbachia. What you need is to neutralize your Agave nature by buying its opposite, which is a Begonia rex-cultorum, and then your relationship will be saved.") He's probably right.
None of this, of course, actually means a damn thing, but hey. If you need to have an answer ready just in case you run into Barbara Walters,4 leave your set of numbers in comments, and I'll crunch the numbers and post your results when I get the chance. You don't necessarily have to subscribe to my interpretation of the appropriate metaphors for each criterion, either. Make up your own and give me those numbers if you like.
1 The similarity is determined by comparing each plant-rating criterion, C, against the respondent's rating, R, for each of the nine criteria as follows:
similarity = sqrt[(C1-R1)^2 + (C2-R2)^2 + (C3-R3)^2 + . . . + (C9-R9)^2]
It's not merely a matter of comparing the difficulty numbers and picking the three which are closest. Consequently, the results that come up may vary considerably in difficulty ranking, owing to differences in how difficulty-rating criteria are weighted relative to one another, and that sort of thing.
2 I ran this both with the metaphorical propagation numbers and the literal ones, and the highest-ranking plant on both lists was P. gloriosum.
3 As not all possible values are represented among the plants, one cannot necessarily figure out what the person is like by knowing what their corresponding plant is. Philodendron gloriosum, for example, is not particularly bothered by pests (I had spider mites once), even though my pest number was very high: it's just the closest fit from among the nine values, among the 300ish plants for which I have values. Dad is totally a Schefflera actinophylla, though.
4 In 1981, during an interview with Katherine Hepburn, Barbara Walters asked "If you were a tree, what kind would you be?" This was of course roundly mocked at the time, though Walters has since defended the question by pointing out that Hepburn brought up the whole tree thing first, by saying she would like to be a tree.
So even if it's not going to help you if you run into Barbara Walters in a dark alley someplace (*shudder*), you never know when it might be handy to have a quick answer ready for questions like this.