...AGAINST THE LORD, for it is by His commission that I am acting in giving the Priesthood to Aaron; and this rebellion is therefore not against “us”
צַ֭דִּיק כַּתָּמָ֣ר יִפְרָ֑ח - "The righteous bloom like a date tree"
(יג) צַ֭דִּיק כַּתָּמָ֣ר יִפְרָ֑ח כְּאֶ֖רֶז בַּלְּבָנ֣וֹן יִשְׂגֶּֽה׃
(13) The righteous bloom like a date tree, they thrive like a cedar in Lebanon;
And in the Medrash we are taught - "What did Korach see that led him to go against Moses? He saw the teachings of the Red Heffer" And this teaching is a wonder to us, however we will explain this matter firstly by looking in the Torah -
וְהָאִ֥ישׁ מֹשֶׁ֖ה עָנָ֣ו מְאֹ֑ד מִכֹּל֙ הָֽאָדָ֔ם אֲשֶׁ֖ר עַל־פְּנֵ֥י הָאֲדָמָֽה׃ {ס}
Now Moses himself was very humble, more so than any other human being on earth.
I granted greatness to Abraham, yet he said before Me: “And I am but dust and ashes” (Genesis 18:27).
I granted greatness to Moses and Aaron, yet Moses said of the two of them: “And what are we” (Exodus 16:7)
But in reality, this isn't a strong claim that Korach has, as we have explained the true nature of humility which we will see now, based on the letter from the Holy Rabbi, Rebbe Avraham the Angel, may his soul be remembered for eternal life that was sent to the Holy Rabbi Rebbe Zusha M'anipoli, may his soul be remembered for eternal life, and this is his holy language used -
"I have great wonder over this righteous man, as myself and Rebbe Zalmina heard from the holy mouth of my master, father, teacher, and Rabbi - "You should know that you are a nothing, but at the same time you are not small, just the opposite, you are great at the same time, based on the path of "His heart was elevated in the ways of HaShem""
And I had written there, that a person, when viewing himself, should consider himself zero and nothing, however, regarding his soul, which is carved from The Creator above, he is elevated to no end - and this is the meaning of the above, you are nothing, and at the same time very great! Because if you consider the soul of a human, it is extremely elevated, and in particular the souls of the righteous who are on an exalted level of the highest.
Based on this, its possible to say, that certainly Moses our teacher, literally saw himself as a zero and nothing, and in the aspect we mentioned above, as he knew that regarding the physical side of mankind is in truth nothingness, however, regarding the soul, and as well in regards to the honor of HaShem and showing the nation His pathways and the loftiness of the soul, Moses would know that certainly on these matters there is no relevance for humility. As the side of him that contains a piece of Divinity within him, Moses was the highest of the highest in the aspect of "His heart was elevated in the ways of HaShem" And in the regard it is very fitting for him to be able to lead the people!
And on the path of thought, we can shed light with what we see with Rabenu HaKadosh, who commanded his son -
..Rabbi Yehuda HaNasi said to Rabban Gamliel: My son, conduct your term as Nasi with assertiveness and cast fear upon your students, i.e., treat them in a firm manner so that they will fear you.
The final line of the mishna states that from the time when Rabbi Yehuda HaNasi died, humility and fear of sin ceased.
Which means that all humans must see things with two eyes, with one eye you should see the greatness of HaShem, and with the other, you should see your lowly status.. and Moses had said "For we are nothing", teaching us he also saw the lowliness of the self, which is not the case with Korach! As Korach only saw things with one eye, which is just the greatness of HaShem, which is why Korach claimed that the whole nation is Holy amongst the congregants of HaShem! But with his second eye he erred, and since he did not see his own lowly state, we see that he was totally unaware that a man can be so humble and leveled when viewing themselves, and only that someone is lofty and great in regard to his soul. Therefor, he erred and said to Moses that you took on too much.
And this is the meaning of when Korach says 'To much for you', implying that you are doing this thing of leading, for your benefit and your pleasure! He was suggesting that Moses and Aaron were just out there to search for honor, and this is where Rashi comes and says that Korach was suggesting that they were taking this position for themselves, and this greatness you are holding, you are doing it for you and not for HaShem.
'To make pure those that are impure, and to make impure those that are pure who say Holy'
This comes to teach us that the purity brought on by the Red Heffer only works on and effects someone with a broken heart, and who sees himself as lowly, as HaShem dwells within the blunted, as well, and dwells amongst the people in their impurity, as its written -
And this is the explanation of 'making pure those that are impure', meaning that Hashem makes pure those that hold themselves to be lowly and impure, but at the same time HaShem is 'making impure those that are pure and say they are holy', which means that those that have an ego and see themselves as highly, they become impure!