Your numbers are fine - but RNA is fragile; making one copy of something really rare will not be able to do anything as it will not last long enough to meaningfully contribute.
Interestingly we now are thinking about ways to use mutations in other ways, youve spent a lot of energy making these polymers, so it would be a shame to waste that right? We think that they can be used to assemble larger functional pieces as mutations are mostly deterministic meaning you'll get the same kinds of errors - so why not put them to use!
> but RNA is fragile
Early on that may have been a feature though, isn't it?
What strikes me as the most interesting thing about life is that almost immediately (on geological time scales) after Earth had developed an environment where life in theory could exist it came to be. That suggests strongly that the mechanism to do so was relatively simple. Then again, the Earth was a vast laboratory and it only has to happen once.
aside: you have the most interesting job!