The first few questions on AB were posted by 'Channel Producers' (including our very own Andy Hughes), just to populate the site and to get things under way.
https://www.theanswerbank.co.uk/History/Question325585.html
However all questions here are numbered sequentially, irrespective of the sections that they're posted in. For example, this question is number 1808798 and the question posted next will be number 1808799, even though it might be posted in 'Technology', 'Travel' or wherever. So, the very first question was (unsurprisingly) number 1, which was posted in 'Arts & Literature' on 1 December 2000.
https://www.theanswerbank.co.uk/Arts-and-Literature/Question1.html