The Fall operates on the premise that all are guilty. This is indeed a classic argument for Camus, but the narrator of this novel goes so far as to suggest that all men are murderers, even if only by accident or through negligence (like not saving others from death). Since the novel was written in the aftermath of WWII, this is a particularly poignant argument. This sort of "universal guilt" makes any attempt at judgment completely hypocritical. A guilty man condemning another man of guilt is absurd by nature.
Jean-Baptiste only pursues power to escape his own sense of shame and degradation. This is why he desires to live above – to compensate for his feeling always "below."