> Society made up by Einsteins would have average IQ 100 as well.

Irrelevant. Which kind of "positive impact on science" would you expect from somebody with an IQ of 100 in the real world, as opposed to your hypothetical "society made up of Einsteins"?

I would expect them to carefuly do the assigned experiments and record the results. If they can be trusted with mounting cars they can be trusted with reading and writing.

Assign same experiments to 10 different teams all over the world to be sure. Would be actually better than unmotivated incredibly bright people hastily doing these experiments once.

Yes the way we do science would need to change but I think it's for the better. It's not like most of the work post-docs do isn't menial.

I think the words you are looking for are "lab technician".

Lots of people with IQs of 100 do science. Science is really simple. You can explain it in a single sentence. Children do science all the time.