In the Torah, the Yom Tov is called Chag HaMatzos. Why do we call it Pesach?
Reb Levi Yitzchok of Bardichev explains it in the following way. The word Pesach indicates what Hashem did for the Jewish people. He skipped over our homes when He plagued the Egyptians. Matzo shows the praise worthiness of the Jewish people.
They had absolute faith in Hashem and left Mitzraim in a rush. They did not wait for the dough to rise, and were satisfied with simple matzos. In the Torah, Hashem refers to the Yom Tov as Chag HaMatzos because He wants to emphasize His praise of the Jewish people.
We call the Yom Tov with the name Pesach, to accentuate our praise of Hashem for saving our lives and redeeming us from Mitzraim.