Last week's parashah, Shemini, teaches us about which animals are pure and which are impure.
In this week's parashah, Tazria, we learn about people, that a person can become impure and then purify themselves.
Shouldn't it be the other way around? First, the Torah should teach us about people, and then about animals.
Rabbi Simlai, a sage from about 1500 years ago, answers thus: In the same way that man was created after the animals, his laws of purity and impurity come after those of the animals.
Why was man created after the animals? Because if he does not follow the will of HaShem, he is reminded of his insignificance, that even a mosquito was created before him.
The Alter Rebbe explains that a person can sink even lower than a mosquito, because they can choose to do something that God does not want. Mosquitoes and other animals do not have the Yetzer Hara—the evil inclination—that tries to lead them away from God. That is why the Torah teaches the laws of purity and impurity for humans after those for animals.
Being impure means being less connected to HaShem. To reconnect and purify oneself, a person must strive, because they were created with an Yetzer Hara (evil inclination).
We generally study the easiest things first and then the most difficult ones.
Since animals do not have Yetzer Hara, their laws of purity and impurity come first. People must put much more effort into reconnecting with HaShem, and then their laws of purity and impurity come later.
For Rabbi Simlai, this was a virtue in man. He said, "It is true, man was created after the animals because of his Yetzer Hara, and his laws of purity and impurity are more difficult. But when he strives, he can connect with God and rise far above the rest of creation.".
Extracted from Please tell me what the Rebbe says.