After the story of Korach, all the pans that were used for the incense test were smelted into a cover for the Mizbeach, with an accompanying warning:
וְלֹא יִהְיֶה כְקֹרַח וְכַעֲדָתוֹ – Do not be like Korach and his congregation.
Rashi understands that this served as a reminder to avoid spurious argument. The Yereim classifies such argument as a sin God, but not to mankind.
But argument is observably detrimental to relationships; why does argument and strife come under the category of sins against Heaven – בין אדם למקום?
Perhaps it stems from not understanding people’s role and specialities.
The Chinuch notes that a Levi who performs the service of a Kohen is subject to the death penalty. Not because of a higher sanctity – because the inverse is also true; a a Kohen who performs the service of a Levi is also punishable by death.
Moreover, abandoning a designated role is also punishable by death. If a duty is as simple as guarding the gates, and the Levi leaves his post to for the singing which is he is allowed to do as a Levi, he is also subject to the death penalty for not doing what was required of him.
Perhaps this explains what the warning is. Everyone is put on this world for a particular reason and function. Everyone has their own abilities and potential that does not infringe on any one else’s – nor anyone else on yours. Missing this is a fundamental mistake and underrates yourself and your abilities.
A Korach claim that everyone is homogenous and ultimately the same, treads all over the speciality of individuals. Like a Kohen who doesn’t appreciate that his work is specific to him, and feels that he can also serve as a Levi, there is a fatal flaw in their understanding of God’s providence, and arguably a certain degree of heresy and apikorsus – perhaps the reason this is punishable by death!
Be yourself. Everyone else is already taken.