Not a pool, parenting will suffice. Just copy the post number from the URL of one image (since there's no real order to these, it doesn't matter which one) and paste it into the "Parent Post" box of all the others.
Parenting makes sense in cases where one or more images is/are related to a particular main image (the parent). In this case, no parent can be identified – they are all peers – which, to me, says pool.
It's probably better to group them in a pool than to leave them like this. If people don't like it, it can always be deleted later.
