i provided a few ideas of how to get data in the other thread.
maybe this:
not first posts, but you can observations by users who created their accounts in the last week:
- Identify page: https://www.inaturalist.org/observations/identify?user_after=1w
- Explore page: https://www.inaturalist.org/observations?user_after=1w
… i think that covers everything discussed here except “rare”, since that’s hard to define. the tools may not provide exactly what you need, but they should get you really close in most cases. if you need more information, just say so.