If there is corruption in one database in an AWS sql server RDS instance, what is the best way to restore that one database? The backups are of the whole instance so you wouldn't want to restore from AWS backups and lose data on the other good databases.
When you restore from an RDS snapshot, you will create a new RDS instance. You do not restore "into" an existing RDS instance.
So you would restore the full RDS instance and use it to:
If you are that concerned about individual databases, then you could keep the individual databases on their own RDS instances.