You can cast Spider Food without a target just to create a Food token. However, if you do choose a target, and that target is illegal at the time Spider Food tries to resolve, the spell won't resolve and none of its effects will happen. You won't create a Food token.

You can't sacrifice a Food to pay multiple costs. For example, you can't sacrifice a Food token to activate its own ability and also to activate Maraleaf Rider's ability.

Whatever you do, don't eat the delicious cards.

Food is an artifact type. Even though it appears on some creatures, it's never a creature type.