There are countless dried pasta shapes, not to mention dozens more fresh pasta shapes. Sometimes the shape you use matters, at least a little bit; when you have a sauce with small solid bits or even larger pieces, it’s nice to use a shape that will catch them, like shells. For soup, you want small pasta that will fit on a spoon.
But as you probably already know, this is not exactly critical; using an “inappropriate” shape is not quite the same as using salt instead of sugar. So I (as an admitted non-Italian) would argue, as I always have, that you should rarely change the type of sauce you’re making because you don’t have the “correct” pasta shape. Use what you’ve got and make what you like. If you have guests from Italy, they might scoff; otherwise no one will care.