Regarding kashrut, from a deeper perspective we must understand the meaning of the Hebrew words mutate - allowed - and asur - forbidden: Why is one food permitted by the Torah and another not?
The word mutate, which is used to indicate that a certain food (or action, word or thought) is permitted, means in Hebrew "unbound", while its opposite asur It means "tied": untied or tied to what?
God creates the universe in such a way that His Will is expressed in a certain place and in a certain way, while if those conditions that He Himself established are not met, that place or object does not express the Divine Will, but the opposite, that which God does not want.
Everything that is in accordance with the Divine Will is called pure. Everything that is not in accordance with His Will is called impure.
It follows from this that, spiritually speaking, foods (or actions, words, and thoughts) that oppose God's Will are "bound" (Assyrum (in Hebrew) to impurity, while those things permitted (mutarím) are "unbound" from impurity and can rise to God.
Taking this idea a step further, even foods (or actions, words, and thoughts) prohibited by our sages (and whose prohibition is not found in the Written Torah itself) also fall into this category of being "bound" to impurity, even though their creation is essentially permitted. This helps us understand what the Talmud says on this matter: "The words of our sages are stricter than those of the Torah.".