How can I bring more attention to my game?

I spent some time designing a thumbnail and game icon in Blender so my game doesn't look unprofessional/of poor quality. I tested it a little bit and I don't think it has any game-breaking bugs or reasons to be boring. In my opinion, I would rather play my game than a much more popular one such as Build to Survive because it's much more challenging and there's a more in-depth build system and weapon system.

I tried advertising it using an image I rendered in Blender with 50 R$. I understand this isn't a lot, but despite having a fairly good CTR (~2%) the people who joined the game only played for 15 minutes at most.

Besides advertising, I don't know how else to get people playing my game. I don't have any popular social media accounts. Are players normally this disinterested in games with nobody else playing, or is there something wrong with my game? Any suggestions or advice will be appreciated.

Here's a link to the game www.roblox.com/games/3382951403/Zombie-Defense-Simulator