I am a high school student who earned less than $5000 last year as 1099-NEC. What is the most someone can make and not file a return? I've seen various figures online.

You are required to file a tax return if you have even $400 on a 1099NEC.   That is self- employment income for which you must pay self-employment tax for Social Security and Medicare.  I hope someone explained that to you when you agreed to work as an independent contractor.   Since no tax was withheld from your pay, you have to pay self-employment tax.

So that you do not have to use the expensive Self-Employed software, you might want to use the Free File software on the IRS site.

Use this IRS site for other ways to file for free.  There are 8  free software versions available from the IRS Free File site

https://apps.irs.gov/app/freeFile/

https://ttlc.intuit.com/community/self-employed/help/how-do-i-report-income-from-self-employment/00/26653

https://ttlc.intuit.com/community/self-employed/help/what-is-the-self-employment-tax/00/25922

https://ttlc.intuit.com/questions/2902389-why-am-i-paying-self-employment-tax

https://ttlc.intuit.com/questions/1901340-where-do-i-enter-schedule-c

https://ttlc.intuit.com/questions/3398950-what-self-employed-expenses-can-i-deduct

https://ttlc.intuit.com/questions/1901110-do-i-need-to-make-estimated-tax-payments-to-the-irs