Who can understand the joke?

It is the snail's frame of reference that has changed. He thinks the tortoise runs too fast. I don't think this is a joke, nor is it a satire on the tortoise. On the contrary, it illustrates a fable of truth. What it wants to express is that in life, you may not be as good as some people who are better than you, but there are still many people who are not as good as you. In their eyes, you are a strong person, so look at life optimistically.