As with much in this early, foundational text describing the primordial events, these verses are easily complicated. Too much can and has been read into the curses brought on by sin. Especially in the curse of the serpent.
I remember one of the early Vacation Bible Schools I was in charge of at the second church I served. We had a chance to have the Fort Worth Zoo visit us one afternoon with a bunch of animals. It was like our own, private Jack Hannah segment from the Tonight Show. The kids got to see, up close and personal, a bunch of wild animals. It was a blast. And the highlight of the night was when they brought out the giant Boa Constrictor. It was scary and exciting all at once. The kids loved it.
What I most remember was the outrage the next day. A couple people in the church were convinced that I had invited Satan into the church. They literally thought that the snake—in fact any snake—was the physical manifestation of the devil. The Bible does not teach that, but they likely got the idea from a convoluted teaching of this passage.
What do we have here?
God begins a pronouncement of the results of the sinful actions of the couple. First, the serpent is cursed. This is one of only two times God actually curses someone directly. (The other is Cain.) In the text we see the serpent being cursed, not the devil. There may be a symbolic aspect of that here, but it is not revealed here directly, nor later in Scripture. There is no mention or explanation of how the devil used the serpent. Mostly because here in this story we just have the serpent. It is only later in Scripture that we see that the devil was behind things.
Secondly, we see some indications of how the serpent is cursed above all other animals. Before he is described as the shrewdest of all animals, now he is the lowest. He and his offspring will creep about on their bellies, and they will eat dust. We are not seeing here that God changed snakes or that they used to walk about on legs any more than we are seeing that snakes now literally eat dust. Later in Scripture we see that the most unclean of all animals creep about on their bellies. (Lev. 11:42) They are detestable. And “eating dust” is elsewhere in Scripture a sign of humiliation. (Psalm 72:9) However, we must also be careful not to read too much into these humiliations. Interpreters like Augustine had some fantastically imaginative ideas about the “spiritual teaching” seen in these curses. The serpent and its offspring carry the burden and shame for its role.
Thirdly, we get the first prophecy in Scripture. As is characteristic with a lot of prophetic scripture, this one has multiple fulfilments. The most obvious prediction being made here is that of the hatred between people and serpents. Easily confirmed, as there seems to be an almost biologically hardwired fear of snakes in humanity. However, the more subtle prophecy being made here fits the more literary, elegant style in the rest of the story. Since the serpent is a stand-in for evil and the temptation of humanity, this curse also serves the bigger story of good vs. evil. Jewish and Christian commentators have long seen a messianic element in this prophecy. Satan will superficially harm the Messiah, but ultimately the Messiah will defeat and destroy the tempter.
Not only did God begin to seek lost humanity as soon as we strayed, He immediately hinted at His plan to save us.