start (life) as (something)
Of a project or product, to begin from some particular, and usually markedly different, status, condition, type, etc. My first novel originally started life as short story, but over the years I just kept adding characters and plot details to it. The soft drink originally started life as a medicine used to treat headaches and anxiety.
start as (something)
To begin some journey or development from a particular status, condition, rank, etc. I started as a QA tester, but I was eventually given the chance to be one of the company's software developers. It started as short story, but I kept adding characters and plot developments until I eventually made it into a full-fledged novel. Hey, don't feel bad—everyone has to start as a beginner. It's only through practice and experience that we get better!
start as something
to begin in some original condition or status. Every forest fire starts as a small spark. The argument started as a small disagreement.