I can't draw. How can I design a character without drawing a reference sketch?

If you have a recent nVidia graphics card, you can use the Stable Diffusion AI to do it for you:
https://www.reddit.com/r/StableDiffusion/comments/x1hp4u/my_easytoinstall_windows_gui_for_stable_diffusion/
It is a lot of trial and error though.
If you need help with construction the queries for the AI, you can use this site to assemble them:
https://promptomania.com/stable-diffusion-prompt-builder/

A friend of mine wrote a book but her sketches for illustrations in the book sucked big time. She found a local art student & gave them her VERY rough draft of the concept she held in her mind & paid them like $5 to turn it into something more pleasing to the eye. That student gave her some beautiful artwork & her book has now been published & now that she’s earning income off it, she’s putting aside a percentage of the profits to surprise the kid with some cash. I’ve heard that you can get the same thing off Fiverr, so you might want to look there. You might even be able to convince someone to accept a percentage of the profits from your show in place of cash now. Good luck in your endeavor!!!

A vivid description would be a good place to start. Think of all the stories told and written over so many centuries about beings of all kinds, including mythological ones. People can picture those characters without the help of illustrations if they are well described.