What is the meaning of the metaphor “It's just a blink, or maybe a smile . . .” (line 115)?

Let’s look at this metaphor in context. In “Called Out,” Barbara Kingsolver writes about desert wildflowers that tend to bloom unpredictably. In the year 1998, these wildflowers bloomed explosively. She describes how there were “whole new species in this terrain we thought we had already cataloged.” She questions: Where did these flowers come from? Were the seeds simply lying in the ground in wait for the opportune climate to bloom? Indeed, she writes, the “magic” of the bloom is in the timing. A seed could have the right conditions to grow, but be hindered by a lack of rain. Kingsolver, however, notes that this cannot be the case for every seed because the different species would simply die off. Desert wildflowers, then, are special. They will not die if they don’t grow in a given span of time because they are “programmed for a longer dormancy.” These plants have developed mechanisms to protect “against a beckoning rain followed by drought.”
In this context of the special qualities of these enduring desert plants, Kingsolver writes:

That is our misapprehension, along with our notion of this floral magic show—now you see it, now you don’t—as a thing we can predict and possess like a garden. In spite of our determination to contain what we see in neat, annual packages, the blazing field of blues and golds is neither a beginning nor an end. It’s just a blink, or maybe a smile, in the long life of a species whose blueprint for perseverance must outdistance all our record books.

Hence, these wildflowers are not something that humans can accurately predict. The flowers we see in bloom each season are not “an end,” but a fleeting stage in the life of these species—they are quick and transient like a blink or a smile. The flowering that we actually see is only a brief moment, and the next flowering could very well be different. The wildflowers are the result of species that will keep changing as they evolve for survival. Kingsolver believes that we will not be able to keep up with these changes so they will forever mystify us.