Earlier quoted context omitted.
I am not a scientist, is this Alien calculus akin (somehow) to a derivative?
The capital delta acts like a "normal" derivative if you want to say so. In eq. 4, you can see the product rule which is one of the most defining features for any sort of calculus. However, I must admit that this summary will take me a lot of time to digest...
But I don't think there's any underlying notion of small changes to something continuous. It is not the slope of some smooth function.