Not eating Unclean food is the puzzle

We often refer to the "Old Testament" when talking about Moses, as if the two were synomous. But that's not the case.

Take the question of eating "clean" and "unclean" foods "in the Old Testament."

Well, that distinction does not inhere in "the" Old Testament, rather, it is a Mosaic innovation.

After all, God tells Noah in Gn 9.3 that “everything that lives and moves will be food for you. Just as I gave you the green plants, I now give you everything."

Recall that there were "clean" and "unclean" animals for Noah (Gn 7.2), although these apparently do not map directly onto the Mosaic dietary laws, since "clean" animals for Noah apparently included all birds and animals that creep along the ground (Gn 7.3, 8).

So the puzzle isn't why the "Old Testament" restriction on eating certain foods lifted in the New Testament, the puzzle is why God placed the restrictions on Israel in the first place, after giving permission to humanity to eat every kind of animal. (See here for my answer.)

Getting the flow points to the exceptionalism of the Mosaic covenant, and points again to the overall teaching of the book of Hebrews, that the Mosaic covenant teaches its own contingency. I.e., it was the exception to the previous Biblical history, which then begs the asking of the question, why? And that's the fruitful question to ask the New Testament authors.