"I'm selling some personal items on eBay - I am not a business"
Yeah, I have said the same, here. And the eBay Loyalists always hit back with, it doesn't matter how many items you sell on eBay, nor of the items origin. What the eBay Loyalists say, even if you only sell one item on eBay, guess what, yep, you own a business.
It appears you are seeking an insurance claim through UPS, and eBay would be the entity whom would have to enact the claim, and it appears they are not interested in doing such, and why, well, that an easy one, what's in it for them: it's just business.
You know, although many shipping insurance claims are honored, and that's good. But keep in mind if you read the small print in shipping entities' insurance policies, it will "most likely" indicated that the shipping container of any product must be approved by the product's manufacturer. So with that said, the time and effort to jump through all the hoops that might be placed in one path to recover any losses through their insurance policies, well, if the amount is small, it's best to keep it small, as the more time you put towards it, well, such only increases the losses.
I know the feeling, though, like in, it's the principal of it.
Good luck
