You’re building a dynamic Apex class so general you’re thinking about promoting it to colonel. You’ve slogged through the Salesforce documentation on the topic, a feat in itself, but are having issues instantiating an empty list of SObjects to be processed in some way.
If you attempt to do this in the seemingly Salesforce manner i.e.
List<SObject> sobjects = new List<SObject>();
You will receive the following error: Compile error: Only concrete SObject lists can be created
