We make mistakes
Speaking of changing our minds, it’s a mighty good thing we can, because human beings are extremely error-prone. We make mistakes so often that we probably spend more time most days correcting ourselves than doing things right. It happens so often, we don’t even notice our incorrect actions much of the time.
Consider how many times you say “Um” and make other meaningless grunts in an average conversation as a segue to correcting a prior statement or adjusting the rest of a sentence before it comes out badly. If we were truly adept at doing things right the first time, every time, these awkward noises would possibly never be uttered.