Noah Arkwright is a commentator comparable to Le Matelot, although with more humor. Arkwright's points are:
there are so many planets that many are humanly habitable;
there are so many intelligences that many are humanly comprehensible -
- so we can bypass the rest.
Incidentally, none of the many races discovered so far is technologically superior. In fact, mankind was the first into interstellar space in its immediate spatial volume. Ythrians and Merseians get the hyperdrive from us. I have been told that technological superiority is a feature of Babylon 5: human and similar races avoid regions of the galaxy where incomprehensible technology is in regular use?
Arkwright discusses an issue that I still find fascinating: human beings getting used to doing regular business with intelligences whose bodies can be of any size or shape. Could you do it - tell your receptionist to send in a visitor whose physical description was completely unknown to you until he/she/yx appeared in your office doorway?
Arkwright quotes a prospector on Quetzalcoatal describing his partner:
"'...he looks like a cross between a cabbage and a derrick...'" (The Van Rijn Method, p. 265).
He also belches hydrogen sulfide, sleeps in mud and passes time not by playing poker but by discussing philosophy. (Well done. Far too many even of Poul Anderson's aliens have a head with two eyes above a nose above a mouth...)
Arkwright makes some further points:
most races have as many individual and cultural variations as humanity;
hence, there can be some overlap with humanity;
nevertheless, a non-human being can show us only his humanly comprehensible aspects;
therefore, he can seem two-dimensional;
Arkwright mentions some stereotypes - Warrior, Philosopher, Merchant etc;
but we can seem flat to him - humanity is a subject of bawdy jokes on many planets.
make the Polesotechnic League period seem very real;
also emphasize that it is a period in which much is still being learned.