I like Scatterlings the best, but that might come across as describing some sort of cute critter.
So I'd pick The Orphan Worlds as more evocative of the setting.
"Scatterlings" is a word that I was pleased to have come across. Formally, it denotes a person of no fixed abode, such as might be a player character in a setting like this. But until you turn to a dictionary it might signify the scattered colonies. But as you say its form and sound might easily suggest a little scurrying or hiding things.
Matt Wilson wrote:
I voted for The Human Reach, purely for Vancian reasons.
Vancian reasons are of course very persuasive.