So to clarify, JenW, if the deposit is brought in by an individual who is working for a private courier service not contracted by the Bank, you check 2d, (don't check "If entity"), and enter the individual's info.
If the deposit is brought in by some individual who is not working for a private courier service (like, the business owner, or a friend, or what have you)you'd check 2b (still not checking "If entity") and enter the individual's info.
You'd only check 2d and "If entity" if the courier is an armored car service, and then you can fill out the rest of the Part I with the armored car company information, not the information of the agent.