This is not allowed - I assume the delivery time was up or almost up when he delivered?
When an order becomes over a day late, the buyer can cancel the order without consent from the seller. If a seller Delivers an order then cancellation can’t be done without their consent (or through Support). This is why some sellers deliver partial orders - it takes away a buyer’s ability to cancel for being late. This is why doing so is against Fiverr rules.
The “Official Delivery” should be made of the full agreed job, not just a part of it. If they want to send you a part of the order they can do so without marking the order as delivered.
If you want to give benefit of the doubt to the seller, there are some sellers who don’t know the rules but regardless, there isn’t any other good reason for them delivering an incomplete order. I would suggest asking the seller when the full order will be delivered and if that is acceptable to you then you could wait. If you aren’t happy with that and the delivery time is up, you could contact Support and ask them to cancel. This will likely result in the seller getting a warning too.
Yes, you are correct in that so requesting a revision was the right way to go. Note that if you hadn’t, the order would have been marked as complete within 3 days so it’s worth keeping an eye on your notifications.