It's neither precise, nor elegant, and certainly not rigorous. On this approach, an item with 1 upvote and 2 downvotes will be ranked below an item with 1000 u

It's neither precise, nor elegant, and certainly not rigorous. On this approach, an item with 1 upvote and 2 downvotes will be ranked below an item with 1000 upvotes and 2000 downvotes, as one commenter pointed out; and in general, bright new items will almost never be presented to anyone. Search on "Bayesian" in the comments for the precise, elegant, rigorous solution below. I won't claim that it's easy to understand, but it's a lot easier to understand than the frequentist ad-hoc version.