What are the most popular student activities/groups?
If you want to be involved seek it out, if you don't want to...then you don't have to. There are many diverse groups on campus & if you don't see one you like then create your own.
Some major ones are the LGBTQ, Campus Crusade for Christ, Inter Varsity...
It's easy not to be involved & it's easy to seclude yourself...but don't. Find a good community to surround yourself with. One who you can collaborate with & one who lifts you up & challenges you to Create Change!