I remember my game being on top after the previous update a couple of months ago and it moved down as other games and updates got released by other creators. Has something changed and newly updated games don't appear on top of "Most recent" and "New&Popular" and stay at the bottom?
Maybe an updated game is given less of a boost than a brand new one, I don't know. But it's also that a lot of new games come to Itch.io all the time. Older games also bob up and down in search results, so that everyone gets a chance. Yours may make it to the top again later, too.