Everything that the author says in chapter 1 is there to tell the audience that they are just as much condemned as the worst people they could think of, the Roman elite.
Going further, the author uses this to set the groundwork for the message of the letter, which is to tell the Christians in Rome to get along regardless of their background.
Ironically, the way that some use Romans 1 to condemn homosexuality is exactly the thing the author is condemning in the letter. According to the letter, they are themselves condemned because of their condemnation. Meaning every person using Romans 1 to condemn others is in error.