Why three types of offerings? Again, I don't know. But, it occurs to me, these might be taken as symbolic of the Christian life. We need to offer ourselves to Christ as Lord when we first come to belief -- first fruits. We need to continue doing so as we become more mature in the Christian life -- ground into fine flour. And we need to continue serving Christ until the end -- baked in the oven, mixed with oil, ready to eat.
There is a discussion of the grain offerings here. It's a pretty good discussion, with some speculation, about the significance of the grain offerings, for the Israelites and for us. (Unfortunately, the author confuses "principal" and "principle.") One thing that the article said struck me. That was that Moses gave these commands to the people in the desert, where wheat would have been hard to come by. Manna, on the other hand, would have been easy to come by, but there was no requirement of a manna offering. See also the Jamieson, Fausset and Brown commentary on Exodus 2. Both these sources offer opinions on why honey and yeast (leaven) were prohibited, and why salt was required. Leviticus 6 has a section on the grain offerings, but it doesn't add much to Leviticus 2.
Remember that Christ used a story about wheat as a parable of winning others to the Kingdom.
Thanks for reading!