Cassini’s goal is to get buyers to the product they want in the quickest time possible, because this provides them with a great customer experience making it more likely they will come back to shop for other items in the future.
It makes sense that the items which have sold the best most recently will be more likely to be what new customers are looking for, and it makes sense that sellers who have sold the most items can be viewed to be the most trustworthy sellers available so long as their feedback is good.
Taking all that into consideration you can quickly understand why Cassini prioritises items which are selling the best from sellers who have sold the most. To new sellers it may seem unfair, but Ebay exists to make mor emoney for Ebay, not for any particular seller.
So the best thing you could do to raise your profile would be to sell in new markets where the competition is low, before trying to break into the more competitive markets.