Here is a list of free APIs. Of course there are thousands more, but these are a few that seem fun and promising for your projects.
Bored API https://www.boredapi.com/documentation
Basketball: https://www.balldontlie.io/
Age prediction (based on name): https://agify.io/
Movies: https://www.omdbapi.com/
Geocoding: https://nominatim.org/
Pokémon: https://pokeapi.co/
Countries: https://restcountries.com/
NASA: https://api.nasa.gov/
Here is a veeery big list of public APIS: https://github.com/public-apis/public-apis