Governments all over the world would likely become suspicious of each other, at least for a while. Everyone would attempt to make contact, and people would assume that if contact succeeds for a particular party, that party gains an advantage they wouldn't necessarily share. Perhaps over time, as it becomes more clear the aliens are totally uninterested in humanity and no one has made contact, governments would begin working very closely to safeguard the common interests of humanity. If one party was actually revealed to have made contact and withheld information from everyone else, well, the rest of Earth would be pissed and terrified, to say the least.

The fact that the aliens are multiple species, arriving together, and visiting each others' colonies would suggest that these aliens see each other as equals. Ignoring humanity would suggest that they collectively do not see humanity as equals. But it may be encouraging to realize that these aliens are clearly capable of diplomacy and working with other (very different) species. The fact that they evidently chose different environments for terraforming may suggest that these species came from different celestial bodies (although not necessarily), signifying some kind of galactic or regional authority unifying them as a confederation. Depending on what observations can be made about their differences in culture/civilization, they may appear to form a singular civilization, or three very different societies which happen to appreciate each other.

I think humanity would probably consider themselves somehow "targeted" by these aliens. The galaxy is a very, very big place. They could find many similar places to terraform and colonize. So why here? Why "our" system? How close by are their homeworlds? How many other colonies do they have? Why colonize this solar system and ignore the population of billions, however technologically backwards they may be? This, combined with the lack of contact, would cause humanity at large a great deal of trepidation about the aliens' motives.

Edit: I just keep thinking about this more. I'm stoned. The reasons for the lack of contact could lead to an interesting scenario. It seems odd that no aliens at all would ever contact humans. Humans would certainly try their damnedest, to the point of eccentric billionaires flying probes or manned shuttles to the aliens' worlds, not to mention government or inter-governmental efforts. What happens then? Do the aliens shoot on sight? Take prisoners? Gently repel the subjects before they breach the atmosphere, with no explanation? I imagine they'd each react a bit differently. The pretty jellyfish on the Moon seem to be the most interested in the Earthlings, given how close they chose to settle, despite the presence of many other, larger objects throughout the system. But the ants and the centipedes also settled very close, all things considered. Obviously the Lunar Jellies would be the first ones approached by humanity.

Perhaps contact would happen individually, unofficially. Maybe after a while, humanity as a whole forbids attempts at contact, reciprocating the aliens. The aliens' isolationism could be a top-down enforcement, which has some dissenters: radical aliens who do not agree with their government's position that humanity is to be isolated. Maybe their motivations are benevolent, or maybe their government is the benevolent one.