Ask HN: How to get a partner for a startup at a garage project phase?

I work on a private project, a set of tests for polyglots. I plan to commercialize it in the future, but right now it's unclear when this happens. Right now it's a website with a minimum-viable thing almost working. I need someone to work together and give a competent feedback, but this is the most tricky problem for me. I'm turning 30 soon, in the past I had good and not so good projects done ALONE, but those made together have been rare.

I show this thing to my fellow language enthusiasts, they like it, but nobody jumps in to suggest something. I'm writing an email to one of them to ask her for an opinion from the user-perspective.

But it feels quite frustrating that it's so hard to make anyone suggest anything. This has been an issue few years ago when I led a discussion club. Social skills are a hard thing, though, I've read the descriptions of various disorders, but however bad I felt and however much I wanted to have such an excuse, they do not apply to me. Asperger for instance? No. I'm agile (do sports) and see social cues well enough.

Still it seems that I don't give others some kind of value. No matter how long I learn social skills. It's just almost impossible to get people interested unless our interests and intentions are identical.

I need a less technical person, better with design skills or one that would use it heavily.

Who has ever made a non-technical person join a web project?

What do people need to join a project? Do I have to praise their insights? (Well, few do say anything rather than 'cool'.) Offer them something? Ask for an opinion beforehand or pretend to show it spontaneously? Talking about the chances of commercializing it? I'm pretty sure of only one thing: they don't care of programming languages and of what's under the hood.

I'll appreciate if you share your experiences.