A new mishnah! With basic directions as to how to make and shape the grain-offerings, with a clear prohibition against "chametz"/leaven, except for 2 specific grain-offerings. Including the source from the Torah to prohibit leaven from the altar. Plus, does each act with offering count as a prohibition (kneading, shaping, baking) or just as one? It's a case of a generalization and a specification, followed by a general case again. The specific statement therefore comes to teach something about the general statement. Note that proximity in the original text matters.