Hi Elle N, thanks for posting the question.
A distribution from an inherited IRA is not business income, which is reflected by Form 1099-R, Distributions From Pensions, Annuities, Retirement or Profit-Sharing Plans, IRAs, Insurance Contracts, etc. to be reported on Form 1040, line 4a, 4b IRA distribution and taxable amount.
In general, business income refers to "gross receipts from your trade or business" which includes Form 1099-NEC nonemployee compensation issued by the payors. Business income is reported on Schedule C, part I Income.
https://www.irs.gov/pub/irs-dft/f1040sc--dft.pdf
https://www.irs.gov/pub/irs-dft/i1040sc--dft.pdf
IRS defines "Trade or Business" - The term trade or business generally includes any activity carried on for the production of income from selling goods or performing services.
https://www.irs.gov/charities-non-profits/trade-or-business-defined
Hope the above helps.
Thank you,
Kitty