Any Song or Musical Work Published in 1922 or earlier is in the Public Domain in the USA. As long as there is no current copyright on the original work, it's probably OK, but public domain can be a tricky issue.
Public domain songs are not inherently free of all copyright protections. Although the original written music is no longer protected by copyright when a song is in the public domain, there are still copyrights that apply to recordings and other issues. No Sound Recordings are public domain in the USA due to a tangled complexity of Federal and State Law. Sampling public domain recordings is not allowed.
However, if you're recording your own original arrangement of an old, traditional song (originally published in/before 1922), you may be OK! You can search the database here if you're unsure.
If it's NOT an old, traditional song, and you're just not sure about the original songwriter, you need to do some research. Covers of copyrighted songs require a DistroKid Cover License. For more information about DistroKid cover licenses, please see the FAQ article here.
It's SUPER important to know the difference. Not opting covers into DistroKid's cover song licensing program can lead to stores taking down your content--or worse--songwriters taking legal action, and nobody wants that!
Note: if you’re distributing a public domain song, make sure to select “I wrote this song, or manage the songwriter (it's an original tune)” on the upload form when prompted.
As long as you're 100% positive there are no other known songwriters, you can list yourself as the songwriter for your own arrangement of a public domain work, or list "Traditional Music" as songwriter.