What are the first 5 integral numbers?

Answer 1

Unlike counting numbers, in the natural ordering of integers there is no "first" number, since each integer has both a precursor and a successor.

Of course, you can use a different ordering, and say that the first 5 integers are 0, 1, -1, 2, -2, for example - but note that this is a different (and arbitrary) ordering, not the natural ordering.

Answer 2

There is no first integer because integers go back infinitely.