Hi Julie...there are courses on every possible topic you think of...selling a course is not bad...the market is only going to get bigger in the next decade...it's better to capitalize on that rather than overthinking about the shitty products...if you are waiting for a truly unique idea to sell a course you won't find one..instead focus on building a specific set of audience and truly engage with them...they will give you ideas on what to sell..and then sell them something that can solve a problem they are actually facing...one example I can think of is Randall Kanna...she sells a job interview prep course and there are already ton of courses selling the same thing....yet she made $53K in just one month...the only edge she had was she built a community she truly engaged with...i would suggest you read this blog post to get a better idea.

https://www.indiehackers.com/post/how-i-made-53-000-in-a-month-with-an-engaged-audience-922b859bf8