I am a one-man band too; many other startups are. For several years I was selling customer database software and learned there are many one-man shops in that category. My customers ranged from small to the largest corporations.
My take is that business customers prefer suppliers of "comparable" sizes. That is, small and medium-sized businesses are ok with one-man shops, but large companies have a preference for suppliers with multiple employees for a business-critical system. To them, it is security and continuity of service. If your software is for personal use, people won't care at all.
Your conversions will be affected by quality of your website or page, quality of the product, support and many other things. The size of your team ranks below all of those in importance - don't stress about it.
Two things I do myself and recommend:
- when communicating with the client on behalf of the company, say "we", not "I".
- if you are using external help - consultants, web designer, etc, list them in the about page as the team who helped you with the product. Nobody cares if they are employees or contractors - what counts is that you have working relationships with them