What should my sources.list look like?

According to the Official Kali Linux Documentation concerning the sources.list file. Your /etc/apt/sources.list should look exactly like this:

 deb http://http.kali.org/kali kali-rolling main contrib non-free
 # For source package access, uncomment the following line
 # deb-src http://http.kali.org/kali kali-rolling main contrib non-free

You can use following command to update the sources/list
echo "deb https://http.kali.org/kali kali-rolling main non-free contrib" > /etc/apt/sources.list