The alternative to believing in an uncaused first cause it an infinite series of cascading causes that has no beginning or "turtles all the way down." It's borderline idiotic.Not at all, I just don't know that existence was the source of all first causes or if it was the result of a cause.
But the most telling aspect of how you are arguing is you seem to be afraid to even consider exploring the possibility that existence is the source of everything.