The sefira period is a time for mourning the death of R’ Akiva’s students who were punished because they failed to respect each other properly. How could such giants fail in such a basic matter of middos? The Shem m’Shmuel offers an analogy: one’s hands do not show kavod to one’s feet for perambulation, and one’s feet do not show kavod to one’s hand for grasping. Kavod stems from the recognition of “otherness”. R’ Akiva’s students were so imbued with the idea of klal yisrael being one united entity that this notion of “otherness” was foreign to them. The mussar haskel is that unity should never cause us to lose sight of individual worth and distinctiveness. As opposed to counting shemita years, which is an obligation incumbent upon klal yisrael as a collective entity and carried out by beis din, “u’sefartem lachem” teaches that the count of sefira must be done by each individual.
The Shem m'Shmuel further explains that the date of La”g baOmer (or Lag laOmer, depending on your nusach) falls out three days after the man started falling (see Kiddushin 38). A recurrence of three times is normally sufficient to establish a chazakah. Until the man began, the Jewish people were sustained by the foods they brought out of Mitzrayim, food tainted with the taste of slavery. La”g baOmer is a celebration of the true start of freedom and break with the past.
I would combine these two ideas of the Shem m’Shmuel. The oppressor does not recognize the individual, but lashes out at the group, whether it is “the Jews”, “the blacks”, or some other collective. This is the mentality of Mitzrayim enslavement. Sefer Shmos opens with the names of individuals - Reuvain, Shimon…, but the new Pharoah refers only to “Am Bnei Yisrael”, forgetting Yosef, forgetting the relationship with the individual. Slavery depends on this depersonalization that causes the loss of respect for the worth of the individual. R’ Yonasan Sacks in Passaic once explained in a 9 Av shiur that the reason the sugyos in Gittin highlight vignettes that relate to the plight of individuals during the churban is because it is easy to lose sight of the scope and effect of tragedy when it is expressed only as the plight of masses. Until Lag baOmer we lived on the food of Mitzrayim, we retained some element of looking at the group instead of focusing on the individual. Even R’ Akiva’s students may have absorbed this mindset, albeit motivated by the positive goal of wanting to fully appreciate the bond of klal yisrael as a people. Lag ba’Omer is the time to break the mindset of Mitzrayim and to recognize the value of individuality.