This comparison doesn't make a lot of sense to me. It's not even comparing apples to oranges, it's comparing apples to the concept of taste.
Furthermore these percentages don't really tell you much regarding efficiency, I'm sure there are less developed societies where computers count for less than 5% of all energy consumption, doesn't mean that their computers are more efficient.
Comparisons are frequently made in other domains as well -- e.g., cyclists measure power outputs in watts.
The rule of thumb I've understood is that the brain runs on about 20 watts (peak power), and a human on average runs on about 100 watts. That's 8.64 MJ/day, which converts to 2064 food calories (kcal), at 4184 J/kcal.
If you wanted to compare them, cite the percent that the CPU uses of its PSU, or cite the percent that human brains use of global energy consumption. Otherwise they're completely different things that have no meaning in relation to each other.
If forced to draw a comparison, you could maybe talk about the energy dissipation of a single neuron and compare that to, say, the energy dissipation of a single transistor. And in that case, considering a human brain is powered by something on the order of 10^10 neurons, the energy efficiency of the brain comes out looking pretty good.
The comparison is valid if you accept the analogy, although I think you could easily dispute the analogy. E.g. you could just as easily view the network of humans in a society as its "brain" and all the things we build (including computers) as its "body".
You could far more easily view the brains of humans in a society as its "brains."
Even this isn't quite true, since it's not fungible, except in the narrow use-case of creating heat[1].
> Whether the energy is carried by glucose/ATP or electric current is just an implementation detail.
This implementation detail means that converting between these forms incurs a tremendous cost (in lost energy) and, perhaps more importantly, is nowhere near instantaneous.
[1] Even the slightly broader use case of heating (e.g. increasing the temperature of a home) can be done with a heat pump, and those don't tend to run off of fungible energy.
Also, your emissions are ultimately plant based, so the only real net emissions are due to producing fertilizers and machinery for agriculture and the embedded emissions in your bike, to the extent those are oil/gas/coal based.
[1] https://ecf.com/news-and-events/news/how-much-co2-does-cycli...