If Leviticus 1 was all about the very basis of the sacrificial system (blood sacrifice) and its basis is the end of life, then Leviticus 2 is all about the celebration of life. The grain offering is an offering of the fruit of the earth. It is the fruit of the toil of man. Man works 6 days a week, and he rests one. His work is to bring food and provision for himself and his family. God is the one that gives that provision. He creates the seasons and produces the harvest. He defines growth, life, and hope. The grain and first fruits offerings are a celebration of that.
With the celebration of life is creativity and choices. I see this represented here in the numerous ways that a grain offering can be prepared and presented. It can come as just the grain with oil and frankincense, or it can come having been baked in an oven, or it can come from a griddle, or from a pan, or roasted in the fire. Each has a reason and a purpose, and each can be an acceptable sacrifice and offering to the Lord.
A common theme here is that in each of these, part of the offering is sacrificed, and the other belongs to the priests. They do not work without receiving from the fruit of their labor, and this is the fruit of their labor.
Also, what is the issue with leaven? YHWH really can’t seem to stand it in anything that is offered to Him. I don’t know why. I know He has His reasons, but i certainly don’t know them.