Taylor Swift wrote "Safe & Sound" at 21 with 3 other different writers. Billie Eilish wrote "idontwannabeyouanymore" mostly by herself at 15. You're right when you say they're not in the same league, you just switched the roles.
At 21, Taylor wrote “Safe & Sound.” Billie Eilish wrote “LUNCH” at the same age.
You’ll never be able convince me that these two are in the same league