It is unclear to me whether all humans together are more powerful than all other organisms on Earth together. It depends on what is meat by powerful. The power consumption of humans is 19.6 TW (= 1.07 + 18.5), only 0.700 % (= 19.6/​(2.8*10^3)) of all organisms. In any case, all humans together being more powerful than all other organisms on Earth together is still way more likely than the most powerful human being much more powerful than all other organisms on Earth together.
My upper bound of 0.001 % is just a guess, but I do endorse it. You can have a best guess that an event in very unlikely, but still be super uncertain about its probability. For example, one could believe an event has a probability of 10^-100 to 10^-10, which would imply it is super unlikely despite 90 (= −10 - (-100)) orders of magnitude (OOMs) of uncertainty in the probability.
It is unclear to me whether all humans together are more powerful than all other organisms on Earth together. It depends on what is meat by powerful. The power consumption of humans is 19.6 TW (= 1.07 + 18.5), only 0.700 % (= 19.6/​(2.8*10^3)) of all organisms. In any case, all humans together being more powerful than all other organisms on Earth together is still way more likely than the most powerful human being much more powerful than all other organisms on Earth together.
My upper bound of 0.001 % is just a guess, but I do endorse it. You can have a best guess that an event in very unlikely, but still be super uncertain about its probability. For example, one could believe an event has a probability of 10^-100 to 10^-10, which would imply it is super unlikely despite 90 (= −10 - (-100)) orders of magnitude (OOMs) of uncertainty in the probability.