In my opinion, the top factors in getting high organic ranking are a high conversion rate supported by high sales. A high conversion rate shows Amazon that customers who find your product are likely to buy it, and high sales show Amazon that the product is being found by the right type of customer.
There can be some variation of course, as a product may have a high conversion rate (for example 50%) but may have only have had 2 views, so therefore only 1 sale. I don’t think this product would rank higher organically than a product that has a conversion rate of 2%, but has many more sales.
High PPC clicks but low sales shows that your product isn’t desirable to the customer for whatever reason, or is being shown to the wrong customer, so this would have a negative impact on organic ranking I believe.
@Fergie_123 made an interesting point about relevancy as well - which is important. If the right customer is seeing the product, they’re more likely to buy it, so Amazon will show it to customers that are similar (based on their algorithms), who are also more likely to then buy it, and the cycle continues.