fastfreddie saidHomosexuals currently have the same rights as heterosexuals to marry in California and in most of the United States.
The current laws in California and most of the United States state that a man can only be married to a woman. This applies to both heterosexual and homosexual individuals. No person can be married to a person of the same sex. This also applies to heterosexuals and homosexuals.
Now homosexuals want to change these long standing laws and allow men to marry men and women to marry women. This has never been allowed before in the United States and in most of the world for most of history (with some small exclusions).
It is no wonder that many people are uncomfortable with these proposed changes. Remember that in some places in the world homosexual activity is still against the law. Remember that 40 years ago homosexuaity was classified as a mental illness by the American Psychiatric Association.
For most of history divorce was illegal, even punishable by death. For most of history women were (and, in some places, still are) denied basic human rights. For most of history interracial marriage was illegal. For most of history slavery was legal.
I see your logic, even understand it to an extent, but it's very flawed. The 'but this is how it's always been' argument has a multitude of examples that shatter it without any effort.
Marriage is not an individual right, but civil contract between two consenting adults.