Hi msweitzer24!!!! And Welcome!!!
I personally would suggest a Betta, with some shrimp or snails, depending on his/her personality. If you're up to it, you could also do a live planted tank! That always makes thing fun
You don't have too many options for a 5g, so a Betta might be your best option.
And if you want shrimp or snail suggestions to go with it, I would suggest:
Red Cherry Shrimp (breed like crazy! Watch out!!
)
Ghost Shrimp (almost invisible, so they can easily hide )
Nerite Snail (my favorite, and they come in so many colors and designs!)
And if you're into a planted tank, I would suggest my favorite low light plants:
Anacharis Elodea (I've had GREAT success!!)
Java Fern (Love the look of them!)
Java Moss (Great plant for looks , and for shrimp if you decide to get them)
Good Luck!!!! Have fun with your new tank!!!