G-d wouldn’t have said not to engage in homosexuality if people were born that way.
I'm no quite sure what you mean. Everybody was "born that way" --- in the sense of born with a strong inclination toward sin. It's called concupiscence, and it's a result of the serious damage done to human nature via Original Sin.
All of us who were "born that way" are still commanded by God's law not to engage in sin.