Although it may be news to you that you “have a business” (and most of the other people who get their first 1099-NEC); The IRS considers anything on a form 1099-NEC to be self employment income.
I'm of the opinion, you should report that as self employment because it's in the general area of your regular work.
If it's a "one time gig", you can report it as "other income". But, if you try reporting the income as anything else, you chances of hearing from the IRS are higher.
Here are a couple of older discussions on this topic (Back when the 1099-MISC was used, instead of the newer 1099-NEC)
http://www.journalofaccountancy.com/Issues/2009/Jul/20091639.htm
https://ttlc.intuit.com/questions/1313326-got-letter-from-irs-about-1099-misc-saying-i-may-be-liable...
