There was a similar one where they found paper aeroplanes in an old schoolhouse, that probably predated actual aeroplanes. Unfortunately the only report is in the Daily Mail, not exactly a reliable source:
Aka paper darts though, maybe slightly datedly, and it is striking how the design there resembles a throwing dart, relatively unlike a modern larger and more forward winged paper plane design.
https://www.dailymail.co.uk/news/article-2111963/Schoolboys-...