I agree about the shorter range increments, but there is nothing in the PHB or DMG about it.
As a poor flyer, your ability to fire a bow does not seem to be affected, but you have to fly at least half your speed, it costs movement to turn in place, and you cannot turn more than 45 degrees in one round.
Greenfig hits with his arrow (rolled 23-2=21 for long range) for 1 point of damage. Gith-Zo has 4 HP left.
Gith-Zo fires back, missing by quite a bit (rolled 15-2=13 for long range). Gith-Zo decides to get closer, moving to 80N80E.
You are now 120 feet away from each other, and it is your move, Greenfig.