Ordinal vs. cardinal. It's "first" not "onest", right? Even the ancient proto-Germanic speakers could tell there's a difference. (In fact, it's basically a contraction of "foremost", and has nothing to do with numbers; their weak numeracy was an advantage on this topic)

If we weren't implicitly choosing 1-indexing it would be 1nd for "second" (and still not "onend" or something). That breaks down once you get to third and fourth, though.

Yup. We should really zero-index century names and years AD/BC as well, but we don't. If we were still using Roman numerals it would be no big deal, but we rarely do, so there's a confusing clash. I'm not sure if it was this programming humour community or another where I had a big exchange on the topic before.

I suppose you could have some kind of positional system that's one-indexed, so 999AD = 1111999AD, and 2000 would be written 2111, but you'd have to completely redo the way arithmetic works, and that defeats the point a bit. And, the new 999 would not be our 999, because it's effectively base 9.

Sure, but you have to see how it's an own goal if you're showing up to table 0.