You have to understand that most (then quickly virtually all) menial jobs will be automated away
A large number of jobs babysitting machines will be created. You know, the same thing that happened all through history: we got rid of highly-skilled, heavily-trained, expensive craftsmen and replaced them with assholes who can operate a lever after five minutes of instruction. Then, we reminded those people we can replace them easily, and paid them less.
I'm mostly ok with your proposal but minimum wage is insufficient to live on so that part is still a stick which is not what UBI should be. Universal social security should be at a minimum, a livable wage.
The 2013 number wwas $546/month per single-adult.
That used a 224sqft single-individual living space, comparing to low-income apartment rents at an average of $1.00-$1.06 per square foot rent, measured in Baltimore, New York, Seattle, and various areas of California, as well as spot checks across the country. The cost of constructing such an apartment was assessed against published lists of materials and replacement intervals, and compares favorably because the kitchen and bathroom fixed costs are roughly $3,000 out of a $26,000 construction cost. Because individuals with a basic income have a known income which can't be lost by termination of employment, loss of working hours, or loss of welfare benefit, the cost of risk in scaling down living spaces shrinks.
With that consideration, the viable monthly rent for such a living space is $237; I budgeted $300/month. That left $246.
Food, using retail prices checked across high and low income areas, was originally specified as $100/month. I've modeled complete food plans in 2016 as low as $25 per 2,000kcal/day over 30 days, but that's rigorous and fragile; the additional buffer is required to control risk.
I also allocated $35/month to clothing and $35/month to personal care. These expenses are more-flexible--clothing obviously can be held onto longer; and soap, tooth paste, laundry care, and the like are overbudgeted--and so I eventually modeled onto a combined $170/month food, clothing, and personal care budget. That gave me enough flexibility for a $45/year Sam's Club membership, utensils, and kitchen tools in one model, even getting so far as purchasing a $200 bread making machine in the fourth month on savings.
Utilities come to $35/month in this model. I used to live in a 750sqft apartment and pay $57/month for utilities; it was poorly insulated, with brick, 2x4 air gap (no batting), and 3/8 drywall on three sides (two long, one short). That includes a $13/month gas customer charge and a $7/month electric customer charge; the landlord can split a single account across multiple tenants to reduce these charges via metering-on-site, although we could theoretically apply regulation to specify a building charge for multi-tenant residences to try to reduce them administratively. Some buildings have shared utilities, but I don't like one tenant's overage to cost other tenants; if the landlord is using on-site metering, they have the same responsibility, except they account for utilities by actual use instead of by equal responsibility.
This leaves $46.49 unbudgeted, with each budgeted expense overbudgeted as a risk control. All in all, roughly 45% of the $549 is a risk control; it's technically possible for a single individual to survive on around $300/month, barely, under perfect conditions. That's unacceptable risk.
The 2014 number is $552/month; the 2015 number was $583/month; the 2016 number is $602/month. That's $331 rent; $188 food, clothing, and personal care flexible budget; and $33 utilities. This leaves $50 unbudgeted. Note that the income actually grows faster than inflation, so these budget numbers are higher than the difference in cost--food costs increased by about 2/3 as much as the food budget between 2013 and 2015, for example, meaning the 2015 budget was $182 but the actual cost was $177, versus $170 in 2013 (food prices increased by ~4.2% from 2013 to 2015; income-per-capita increased by ~6.8%).
So yes, it's enough for one person to live on.
There are also considerations in there for aid for children of low-income households, since they don't receive a UBI, being that we'd have to provide a UBI sufficient across the entire variation--that is, almost every household would have to end up with money left over after childcare expenses, thus pumping out and neglecting children is profitable, or else the childcare welfare isn't actually enough to care for children. Because the risks of a public aid welfare for childcare are known and actually quite low, scaling that model down to specialize in childcare welfare works well.
I've actually put numbers to this shit, not just feel-good ideas about what is and isn't enough to live on. Do you want something that actually works, today, and in the future; or do you want idealistic bullshit that we can't afford, that won't work, and that will cause economic collapse if attempted? People die for unrealistic ideals--real people, with lives that could have been supported. We actually can end homelessness and hunger in the United States today. Bullshit fantasies about a world where nobody can remember how basic physics works because the machines have become our lords and masters and we have become the cattle have no place in civilized discussions.