First of all, it is clearer to speak, and think, of ownership of a copyright, not as ownership of the music. That helps focus on the rights that the parties actually have.
Secondly, notice that the license granted by agreeing to the quoted terms id "non-exclusive". This means that the grantor (who is probably the artist, but might not be) retains all of the rights given by the copyright that are compatible with such a license. The copyright holder may grant similar licenses to others, provided that such licenses do not purport to exclude the license granted to TuneCore. The copyright holder may also sell or transfer the copyright to someone else in toto (such as by gift or inheritance), but the copyright will remain subject to the given license.
Thirdly, the license granted is on a specific recording. it does not convey the right to make new recordings of the same musical composition. That right is retained by the holder of the copyright on the music. That copyright is often not held by the same person or entity as the copyright on the recording. The initial copyright on nthe musing is held by the composer(s) (unless, in the US, the music is a work-made-for-hire (WFH)). The copyright on the recording is initially held by the performers,(unless it is a WFH). Only when the composer(s) and performer(s) are the same will the copyright be held by the same person. But even if they are the same, the license granted by agreeing to the quoted terms does not grant any rights over the composition, such as the right to perform the work publicly, the right to make new recordings, or the right to make arrangements or other derivative works based on the composition. Note that in the US the right to create a new recording may be subject to a compulsory license, known as a "mechanical license" under 17 USC 115. In general only works with published recordings are subject to a compulsory license. (This is known as a "mechanical license" because it was first created to accommodate music for player pianos. )
Fourthly, although the grant is stated to be "irrevocable", in the US such grants my be terminated under 17 USC 203 during a period of five years, starting 35 years after publication of the recording. This right may not be waived by contract in advance, any contract provision purporting to prevent such terminations is void under US law.
In addition, "moral rights", which include the right to be identified as the author of the work, are granted by the copyright law of several countries, and may not be waived by contract. The US grants such rights only to the creators of works of visual art (under 17 USC 106A) but many European and other countries grant such rights to all creators of copyrightable works.
So the copyright holder(s) retain quite a few rights after granting such a license as is specified in the4 quoted terms.
