With the exception of Tarzan, since we arrive to this world we have to coexist with our fellows: with our family, in the kindergarten, in the school, with our friends, in the old people's home...
If the simple coexistence between two people can make sparks fly, just imagine what might happen in a house inhabited by 6 beings with completely conflicting personalities.
The Glumpers are a gang, a group of friends living together whose opposite and extremely stereotyped features will interact continuously.
Their place, their home, will become some kind of nuclear reactor in which the minimal interaction between its particles might cause a chain reaction of disastrous consequences.
Externally, a Glumper has nothing in common with a human being, that's true. But if we pay a little bit more attention to their behavior we'll find out that they are our spitting image.
We are unaware of if the Glumpers believe are atheists, but we know for sure they can't help practicing almost all the deadly sins: gluttony, greed, sloth, wrath, envy and pride (not lust as, though they're always naked, it is still not proved that a Glumper feels any kind of interest by sex).
Seeing a Glumper, human beings can feel fraternity and relief in equal proportions.
Fraternity as he will see that is not the only specimen in universe capable to feel such these base instincts. And relief, because if between humans a simple discussion will generally end up with only a couple of insults, in the case of the Glumpers it can finish in the best of the cases in an atomic explosion.