The insect with 4 legs that have feet is more interesting. Take a look at some pictures of grass hoppers and locusts and you will see 4 legs at the front of their bodies and 2 at the rear that are very different.
The problem with your statement is that fact that the beetle is listed in this group as well. The beetle does not have a drastically different set of back legs like the grasshopper and the locust does. And since these are all listed in the same group, it would make sense, especially in the Hebrew in which it was written, that all these insects are considered of a same kind with four legs. The beetle obviously has six legs.
What is meant in the text by the statement "which have legs above their feet"?
It means what it says. It is a simple term. It means its leg are above its feet, not below. So you have a description of legs that end with feet.
As you say a bat is not a bird, at least, it is not a bird by todays definition ... You must remember, these commandments were given to a simple people (by todays standards) some 3 to 4 thousand years ago with the intent of relaying Gods instructions in a way that they would understand. Would they have understood If it was said "of the mamals you must not eat the bat"? I don't know and cannot answer.
However, the Bible is supposedly written by the god who knows everything and is perfect. He would know that a bat is not a bird and, therefore, would not include the bat in a list of birds nor would he use the Hebrew word for "bird" (
tzipor) when describing them. He could have done a number of things when communicating to the ancient Hebrews:
1 - He could have listed the bat in its own category apart from any mention of birds
2 - He could have taught the ancient Hebrews that bats are not birds and then included them in the proper category of unclean animals that are not to be eaten.
However, this was not done.
The only real similarity that a bat has to a bird is that it flies. However, so do other animals and they are not listed here. It is very obvious that bats are different from birds as they do not lay eggs, do not have feathers and bills, they have teeth, etc.
