This is caused by the use of unique: true in the schema.
You probably have to delete the collection as well. Atlas dashboard > Databases > Browse Collections > Delete the “people” collection.
Now try the submit again.
Edit: as an aside, you really do not want your connection string with the username and password in the code. Use a .env file (or the secretes tab on Replit). I guess it’s OK when asking for help but then you should change the password afterward.