Wikipedia quotes a paper saying people make / recycle around 50 kilograms per day. That would imply that people make around 0.5787 grams per second. But this is in tension with the idea that people use 100 watts at rest. Since that 100 watt number seems to be more strongly established, I think 1 gram per second is a better estimate.
The cited paper in Wikipedia might be accurate and the author is just expecting "at rest" to mean awake but mostly idle. I'd wager that during sleep, we use less than 100W. For the sake of argument if you take out 8 hours (asleep time) from a 24 hour period, you end up with a rate of ~0.8681 grams per second, much closer to 1g/s. Anyway, just a little fun with numbers.