I have never heard about the idea of homosexuality preceding the days of Noah so much as the Earth was filled with violence. If the fact that Lamech, a descendant of Cain maintained an oath of secrecy and murder, then the real, though not sole issue, preceding the days of Noah was people forming a bunch of Mafia organizations and murdering each other. This is further supported by God telling Noah after the flood that murderers should receive the death penalty.
Read Romans ch 1 vs 25-27. Those verses describe homosexual acts that Paul cites as having been universally practiced by both males and females in the antediluvian world.
As you said, Paul also cites murder and nature worship as widespread sinful practices (vs 21-23) that caused God to destroy the antediluvian world. However, he gives equal weight to the apparently common practice of homosexual sins as another cause for God to destroy all the antediluvians except righteous Noah and his family. I think that today's world is probably even more depraved in God's eyes than the antediluvian world was, and He says that it will be destroyed by fire next time.