Some fantasy works (e.g., the Shannara series) are clearly set in the far future of a world essentially indistinguishable from ours. There are a few hints that the Craft Sequence is one of these: in Three Parts Dead there's passing mention of the ancient world having used "black oil" (or something to that effect) rather than gods or craft to achieve its marvels, and in Two Serpents Rise the protagonist quotes from Casablanca.
However, that doesn't seem consistent with other features of the world, for example the gods and spirits native to Seven Leaf Lake. Were they supposed to be created somehow after technological civilization fell? Or perhaps they were always around and we just don't know it - but if so, why don't we find that irrigation projects and the like are always being mysteriously sabotaged, as RKC feared the lake spirits would do?
Or perhaps the world of the Craft Sequence was just never all that similar to ours, apart from a few details like Casablanca and the use of oil?
Is the Craft Sequence set in a world that was once much like ours, or not?
[Word of God preferred, but I'll also accept any reasonable argument based on the text. Please note that I'm only halfway through Two Serpents Rise so please try to avoid spoilers, or at least hide them and I'll check them out after I've finished the book(s) in question. Thanks.]