Your characters have traits in common with you. They also have things different from yourself. Likewise, their stories will have elements of your own life, but will be unique and varied. A lot of one-shot or short writing careers seem to be of the variety where the author clearly has something they want to get across.
If they are subtle about it, they might get away with several stories tied into the theme. Many are not very subtle. Don’t fall into this trap. Even very good authors can fall into this trap. When they find something they feel strongly about, it becomes a part of their writing. That is fine of course, unless it consumes all of their writing.
I know of one author whose older works were amazing, but as they grew older, more and more their stories centered around the same three or four elements repeated regularly across several different series. Not in a minor way, but to the point where you could actively swap out characters without feeling like they were any different.
Now, there is nothing wrong with having a cause. Some authors have turned this to good effect. A psychological viewpoint is at the core of the Gor novels. Love of languages and ancient traditional stories formed the core of the Middle Earth designs. Lovecraft’s works all had central themes and a common mythos regardless of the story or novel in question. Each of these ideas was drawn out into a workable and extensive collection of popular fiction.
What is the difference? Arguably on Gor, not much. For the other two at least, it was that the authors put their passions into the work, but without shoving their own philosophies down our throats. They told a good story first and concepts second. They didn’t forgo the flow of the story just to push an idea. When you write, put your passion in. Just don’t get so caught up in putting forward a moral that you forget to tell a good story.
Moreover, understand that not everyone is going to agree with the moral of a story. Morals are subjective. What I feel is something that everyone should know and understand is something someone else feels is utter rubbish unworthy of a second glance. If I am telling a good story, they will hear it out and maybe even empathize on a certain level. If I preach at them, they set the story aside and never come back. Most likely they will never read another thing you write, tell everyone they know to avoid your tripe and your message would be lost anyway.
So, enough of my own soap boxing. Hopefully you will find ways to tell not only the morals you feel strongly about, but also just tell good stories. Not every story has to have a moral you feel strongly about. Not every character has to overcome every flaw they have. Let the stories have a life of their own and if it happens to fit your own world paradigm, so be it.