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.
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/