How to re-upload an image but not removing it
It's not really clear what you're trying to achieve, but basically there are two ways to go:


Don't use an image field, but use an "entity relation" to a media entity instead. (Media is a core module >= Drupal 8.4, or a contrib module &lt;= Drupal 8.3)
User revisions: Create a new revision of your node every time you update the image field. You then can view older versions of the image in the version history of your page.