If you like to stay safe and hate taking risks, you're unadventurous. You prefer to keep your feet firmly on the ground while your fearless friends try bungee jumping or skydiving.
Unadventurous people aren't interested in extreme sports or unfamiliar food or anything else that requires a degree of boldness and daring. You can also talk about unadventurous menus (featuring boring or familiar food) or unadventurous art at a gallery show (with pleasant, familiar works of art rather than innovative ones). Unadventurous adds the un- ("not") prefix to adventurous.