Are there websites where I can do simple tasks like distinguishing/sorting images, writing captions, selecting correct options or other tasks I can do in my free time or mindlessly whilst also contributing to meaningful projects? Something like Google Crowdsource, although I would like to avoid registering to any privacy invading services asking for my personal info in order to contribute.
My friend, the Zooniverse needs you. Go do some science!!
Another good one is https://commonvoice.mozilla.org/en/ where you either read out text or validate recordings by others. These samples help creating artificial voices.
Here it is, all for you https://open-assistant.io/
You also get a useless leader board to replace reddit karma!
It is anyway a legit initiative to help for open source LLMs
Great that you are looking for a way to contribute to something meaningful. OpenStreetMap aims to create a free map of the world, at detail levels nobody else does. Besides the obvious, it helps groups that are marginalized (how do I navigate as a blind person? Where are safe spots to cross the street? Does this restaurant not only have a ramp for my wheelchair, but does it also have restrooms that accommodate for my needs?)
The simplest way to start is to contribute on https://pic4review.pavie.info/ - here you can basically look at pictures other people have taken, answer some questions and thus add data to OpenStreetMap.
OSM is fantastic, but I want to direct OP towards their Humanitarian Aid page where you can contribute to emergency mapping projects: https://www.hotosm.org/
