Articles created without a category should be tagged with a maintenance tag. Use the {{ Uncategorized}} tag to put articles in a maintenance category. Optionally add a date parameter like {{Uncategorized|​date=​April 2024}} to put articles in by-date maintenance categories.

Such tagged articles are found at Uncategorized pages. You can try to categorize articles yourself. One useful technique is to follow links in the article to other similar articles and see how they are categorized, so you know what to copy.