I am 11 years old, and I have made an app I want to post to the App Store. Is there any way to do that, or do I have to use my mom's account? (I have an Apple id because of Family Sharing)
The Apple discussions thread can i be an apple developer under 18? is exactly what your are looking for :
No. An adult would have to do that for you. To have a developer account you must be 18 or older.
You can always start a corporation and the individual age restriction is not relevant anymore.
Yes and no.
Strictly speaking you need to register as a developer and to do that as an individual you need to meet minimum age requirements. Typically this is 18, although it could be different in various countries.
Also, depending on your jurisdiction, there may be other requirements you must meet before being able to register as a developer.
In your case, you could have a parent register and then use their developer account. When uploading an app you need to complete a number of metadata fields, one of which is who the app is copyrighted to. So you could still put your name in that field.
Another option is to set up a company (or something similar) in which case there wouldn't be the age restriction. However, depending on your jurisdiction there could be an age requirement for registration of a company.
A good place to start (if you haven't already) is to explore https://developer.apple.com for answers to your questions.