Trying To Be An Entrepreneur, But I'm Evidently Not The Entrepreneur Type

Please be patient with me - I want to get better, but I have a very employee mindset.

Long story short, I (33M) was brought into an alcoholic beverage-selling startup with a very small team. I was brought in through a connection, and I see potential in the startup, so I'm sticking around but I have no idea what I'm doing.

My background is more towards design and marketing side, however I don't have a very defined role here.

I report to my supervisor who makes many things happen, finding leads, organising events, client follow up, you name it. My supervisor told me that I basically need to stop seeing myself as a designer and more as one of the managers.

My problem is it's very difficult for me to think beyond my direct scope of work. I don't lie awake at night spinning up new ideas to improve the business, and my idea of "good enough" is never good enough to any of the managers. I'm also severely inexperienced in any sales or client-facing activities, and being thin-skinned is one of my biggest weakenesses (I hate to inconvenience others).

I'm starting to feel extremely useless because my ability to contribute boils down to ad hoc and supporting activities, which has its value but it isn't quite enough moving forward. My supervisor has to micromanage me quite often, which I kinda appreciate because otherwise I have no idea what to do next.

I value my down time, which I suppose is another way of saying lazy. What can I do to help me into the mindset for what's to come next?