Is Ethernet's data link layer using MAC addresses an abstraction of the physical layer? The physical layer is the only layer where bits are actually moved. It all depends on your point of view.
Each layer has its own purpose and they all need to work together for a complex network to work.
The transport layer's job is to allow communication between applications running on hosts. An application doesn't have to care about details in between.
The network layer's job (e.g. IP) is to allow communication between hosts across an arbitrarily large network using logical, grouped addresses. The network layer doesn't have to care about physical connections and how a network is actually built.
The data link layer's job (e.g. Ethernet) is to a allow communication between hosts (interfaces) connected to a shared local area network. This is mostly point-to-multipoint using MAC addressing ("physical" addresses). The data link layer doesn't care about how its frames are actually transmitted.
The physical layer's job is to move bits from one place to another. Usually, that's point-to-point, from one end of a cable to the other. It's only here that link speeds, media, distance, line codes and such matter.
Each layer somewhat multiplexes and refines the simpler layer below it. The functionality increases going up each layer.
Yes, each layer is a kind of abstraction of the one below. But it is also much more, introducing another level of functionality.