Unfortunately the IRS is not being very transparent about this process.  Some people get direct deposit, some people get checks, some people get debit cards, some people get nothing.

If the attempted direct deposit failed then they should issue you either a check or send a debit card to your mailing address on file.  The USPS does not have a good reputation these days (and for good reason IMO) for actually delivering the mail to the right place or in a timely manner but keep in mind we're coming off of a holiday weekend.  So give it a few weeks to see if something arrives.  You may also get a Notice 1444-B in the mail indicating that your payment has been sent.

The IRS recently announced that individual filing season opens on February 12, 2021.  If you don't get the Economic Impact Payment by that point, you should file a tax return claiming a Rebate Recovery Credit (RRC).  There's nothing you or anyone can do until then.

Conclusion:  Everybody's right.  A paper check might be sent, a debit card might be sent, you might need to file a 2020 Form 1040, and you are in the wrong place on the Internet.