When you import contacts, keep in mind that a contact can be an organization or an individual. 

If it's an organization, you can import into

• Organization Name
• Organization Contact Person

If it's an individual, you can import into:

• Title
• First Name
• Middle Name
• Last Name
• Suffix
• Spouse Title
• Spouse First Name
• Spouse Middle Name
• Spouse Last Name

You can't import into both the organization name fields and the individual name fields.