Why is Kosher important to Jewish people? It is not necessarily healthy food from what I can see.
Since I don't believe the question as stated is a dupe:
The laws of Kosher fall into a category of commandments called "chukim". That is, that G-d gave them to us without explaining or giving a reason for them. Through the ages, certain sages wrote many pages giving possible rational explanations, but ultimately, we do not know the reason that G-d gave us this commandment (or any of the commandments in this category).
So in short, the reason Kosher is important to the Jewish People? Because G-d said so.