The Necessity of Humility in Order to Truly Learn

There are several reasons for this, many of which have to do with Moshe Rabbeinu’s great humility.
Seeing as the word l’alef means “to teach,” the Kli Yakar combines the letter’s diminutive size and meaning by stating:
It hints that learning does not exist other than in he who makes himself small.
And therefore, it hints at how Moshe made himself small and fled from power and said, “I am not a man of words” (Shemot 4:10)….
This is not always true, of course.
Yet many (but not all!) people who possess high scholastic aptitude tend to also feel innately better and smarter than the average person—even though many geniuses obviously make foolish mistakes in both their personal and professional lives, and can behave with far less integrity, too.
Yet because they are often given the message since childhood that they are innately better & smarter than others, many academically intelligent people seem to feel this is true without reservation.
But the small alef here indicates that, on the contrary, people cannot internalize what they learn unless they humble themselves from within.
This explains why those who consider themselves superior often behave with such a lack of intelligence.
And this explains why those who only intellectualize their Torah knowledge behave as if they lack Torah knowledge. Their lack of humility actually blocks them from truly absorbing all the Torah they learn.
Or perhaps in other words, for better or for worse, a person's absorption of Torah values parallels one's level of humility.
Greater Power Means Greater Responsibility
The practical reasons are clear, but there are also spiritual reasons as to why wealthier transgressors need to sacrifice a bull, while the poorer ones need to sacrifice birds, and impoverished need to sacrifice simple grains.

The practical reasons are clear, but there are also spiritual reasons as to why wealthier transgressors need to sacrifice a bull, while the poorer ones need to sacrifice birds, and impoverished need to sacrifice simple grains.
First of all, the Kli Yakar points out that the wealthier one is, the more prominence, power, and influence one has.
A wealthier person also has access to a better Torah education.
(Especially in the Kli Yakar’s times, books and tutors were the luxury of the rich.)
Therefore, a transgression on the part of a wealthy person contains a similar quality to that of a horned animal who can gore at Heaven, so to speak.
Finding the Balance Between the Extremes
The Kli Yakar explains the necessity of physical desires and how to balance these physical desires with spiritual desires:
Each person has his desire for all the delights of This World as symbolized by honey because just as the honey is sweet to the palate and too much causes harm, then likewise are the delights of This World; they are necessary and too much of them causes harm.
So this is the counsel that is advised:
A person should utilize that which is necessary and that which is extraneous, he should deny himself.
And the leavening represents the yetzer hara [evil inclination] and like Rebbi Alexandri said in his prayer, “Our will is to do Your Will, but the leavening that is in the dough is obstructing” (Brachot 17).
And these two are necessary for the existence of Man because if he wouldn’t attend to his essential needs—which are symbolized by honey—he would die.
And he wouldn’t live and his limbs wouldn’t be strong and healthy to toil in the mitzvot of Hashem.
And if there was no yetzer hara, a man wouldn’t marry a woman and he wouldn’t build a house and the world would be desolate.
And these two things precede time-wise to occupying oneself with Torah and mitzvot because if a person wouldn’t first eat flour, there wouldn’t be Torah.
But occupying oneself with Torah should be one’s first intention and priority because just as the leavening and the honey that we mentioned lack the totality [shleimut] on their own to raise a pleasant aroma [rei’ach nicho’ach] to Hashem, yet they are a priority and come first for a person, because through them, he can attain spiritual perfection [shleimut hanefesh].
This is my own translation and any errors are also mine.