Hey! Hopefully this helps out a bit! The game looks great so far; But, in order to keep players coming, and make it more interesting, I would add multiple different levels, possibly even randomly generated. To monetize it, add certain passes, such as skip stage/level for about 25 ROBUX. You could also add and create different in-game effects; I noticed you have multiple different types of in-game currencies, such as coins! Use these in a possible in-game shop you could make, whether that be a player teleport, or a GUI with a shop in it. You could add a lobby where players spawn, and make this a round-based game, where you wait for players to complete the level, and upon completion, they are teleported to the lobby, where a shop would be located.
There are many ideas you could add to make this game hold players and make it bigger; multiple of which I stated above. In order to make the game less bland, I would make the levels look less different, and make different obstacles on the course, other than a log; for example, a spike roll could be a very interesting, scary, and fun obstacle, and could present players a fun challenge. You could add visible death blocks on the track, for players to jump over, just like a log; Be sure to make sure the log cannot hit a player while they are jumping over the obstacle. This is something you’d have to do through testing and figuring things out, and game designing. It’s an amazingly fun challenge to test out things like this in games.
You can also add difficulties stating how difficult/easy each course is, within the lobby. You can make a map voting GUI for the levels chosen if you choose to do it this way, and within that GUI could be difficulties displayed. As @TheSenorDuck stated above, you could add speedrunning leaderboards to your game, which will make players stay in-game for longer times, and will make them want to compete for faster and faster times, hopefully bringing in more players over time. You could add trails to the game, that follow behind a player whilst they are running. This would also get players to play more, as some would want to get better and better trails. For trails, if you know how, you could add a trading system, and rarities for each different trail. However, that’s optional, and I only recommend it if you have been developing long enough to feel you can undertake that challenge.
All in all, there are many, many, different ways to make your game keep players and make a “good” game; Use a document to store ideas you may have and make, and keep an eye on that, adding those to the game, and making sure they get added, while keeping motivation and being sure not to rush yourself, and to rake your time. In my personal opinion, a good game is not made by it being large and full of content, a good game is made by quality work and a fun and engaging as well as unique idea. You have this so far; keep it up. Good games are quality and not quantity; start your game with smaller updates and don’t try bigger updates until you feel ready. You may feel burnout if you go to fast, and may even feel loss of motivation. This is all just a part of developing, and you will eventually get over it and feel better. I have many replies stating how to deal with burnout and things like that, so if you feel these, and don’t know what to do, be sure to search for those.
Good luck with your game, and have fun making it!