Nothing is EVER a sure success.
But you’re going to have to have documentation on profitability from a LARGE test market group, at least 100,000 people. How many claims per 100,000? What’s the cost of the product? You’ll need a legal clearance study to make sure the product is legal. Not to mention, which state insurance commissioners will approve it?
Companies probably aren’t going to BUY an idea. That’s why there’s no interest – it costs A LOT to turn an idea into a feasable product. You’re going to have to do SOME of that legwork, to make your concept sellable.
And hey, it could already be out there, and you just don’t know about it.

Only executives in distribution can get their company to sell a new product, after it’s cleared through state comm depts. If you don’t want to go that route, try getting in touch with private insurers, like Lloyds of London

The last thing the average American is open to is more insurance.
We are already insurance and taxed to death. Although insurance is necessary, it is considered a necessary evil.
You never need it, until you need it.
By the same token no one ever thought pet health insurance would sell, yet it does.
You need a group of investors who believe in your product and then start your own insurance company.
Just realize that insurance is one of the most regulated, hardest to run, industry in the country.

You said “non-life and individual” like accident and sickness, liability?? You might want to find a convention to go to to pitch your idea to a few execs. You also have to make sure that your idea is marketable.