This question has been asked very often. The answer is: It is difficult. There are multple new games released on itch every day. A lot of them have good or decent quality, but most of them will attract no attention at all, just because there are so many. So either you have to stand out a lot, or get very lucky.

What I recommend: Trade feedback with others and constantly improve your game. Maybe you can create a really good game in that way, or you learn from your mistakes.

Post anywhere you can. I share my stuff on Facebook, on the GDevelop forum (the development platform I have been using), and on a classic Doom forum where they have a section for creative works that aren't doom mods. It isn't a huge amount of traffic but I do get views from all of those sources, in fact I get a lot of people coming from the GDevelop forum even though nobody has commented on the thread itself. So you might want to  consider posting on the Unity forum if you haven't already, in the WIP or Made With Unity sections.

The next step after that would be to get into more marketplaces. If you think about it from a player perspective, most people only look at the one or two online stores that they are already using. And for average players that will most likely be the biggest ones such as Steam and Google Play. If your game isn't discoverable on one of those, you're missing out on a big chunk of the gamer population that doesn't know about or frequently browse itch.io.

Work hard build a following stay consistent. Engage with your audience