Just a tiny piece of personal experience, without any pretense of methodological value.
I started my new novel writing a single chapter, just for the fun of it, I liked the central scene. I had no idea it would have become a novel. Then someone read it, and they loved it, my motivation grew, and I added a second chapter, and a third, always maintaining its coherence. It became a short story, now it is a 50,000 words novel - and growing.
Miraculously, the plot and characters grew with the text. The original scene is now Chapter Twenty-Three. LOL. I don't know how good the novel is, but writing it this way was fun! And it is definitely a low-cost approach.
So, you could just take the chapter you like better, featuring the character you love most, and build a new story around it, I guess other chapters you wrote will come in handy throughout the creative journey... but actually, I don't know if it could work for you or for other friends.
It is just my tiny piece of personal experience.
Greetings from sunny Italy
Jo, near Venice