Your aliens are more communally minded than humans.
Motivation and world view among human cultures involve a balance between the needs and desires of the self (and family), and the needs and pressures of the community as a whole. One hears about traditional asian cultures as more of the later, where the individual considers herself second and the community as a whole first. White Americans stereotypically consider the needs of the individual first and the needs of the community second. It is a spectrum.
Your aliens are all the way out on the community side of this, to the point where compared to the aliens, traditional Koreans look like Texas ranchers. The alien collective is closer to a hive or a social insect than any human society. As Star Trek Vulcans lack emotions (or have completely repressed them) so these aliens lack a sense of self. Individuals readily sacrifice themselves for the greater good - for them the concept of "self" is even a tricky one, useful for locating an individual's body in place and time, but not particularly for the needs and drives of the individual which are completely subsumed by the needs of their group.
"Greed" necessitates a strong sense of self, and desire by the individual to exclusively own the belongings of other individuals, or exclusively own more belongings than competitor individuals. In this society, other individuals are not competitors. The aliens would understand greed, having seen animals greedy for food. It is not something they experience themselves.
If otherwise like humans, these aliens could be formidable competitors to humans. Our human competitive sense trips us up when operating as a group. These aliens will not be tripped up in that way,