How to use only 1 method for 2 objects which different class type

I have two objects, the difference is that there are two other classes, and both classes are inherited from the object class. i made code which can create, delete, save or load. So both objects are created, deleted from world, saved or loaded to asset by method

this is for object a

             void CreateObject()
             {
                 PersistableObject instance = Instantiate(persistablePrefab);
                 Transform t = instance.transform;
                 t.localPosition = Random.insideUnitSphere * 5f;
                 t.localRotation = Random.rotation;
                 t.localScale = Vector3.one * Random.Range(0.1f, 1f);
                 persistablePrefabs.Add(instance);
             }

and this is for object b

         void CreateShape()
         {
             ShapeOfPersistableObject instance = shapeFactory.GetRandom();
             Transform t = instance.transform;
             t.localPosition = Random.insideUnitSphere * 5f;
             t.localRotation = Random.rotation;
             t.localScale = Vector3.one * Random.Range(0.1f, 1f);
             varietyShapePrefabs.Add(instance);
         }

As you can see that both methods very similar, only different thing are list and class type

my question is how can i use only 1 method for 2 different class type objects

this is my full script

  public class PersistableObjectsManager : PersistableObject
     {
         public KeyCode createKey = KeyCode.C;
         public KeyCode newGameKey = KeyCode.N;
         public KeyCode saveKey = KeyCode.S;
         public KeyCode loadKey = KeyCode.L;
 
         public PersistentStorage storage;
         public enum ScriptType
         {
             PersistableObject, ShapeVariety
         }
         public ScriptType scriptType;
 
         [Header("Persistable Object")]
 
         public PersistableObject persistablePrefab;
         List<PersistableObject> persistablePrefabs;
 
 
         [Header("Shape Variety")]
 
 
         public ShapeFactory shapeFactory;
         List<ShapeOfPersistableObject> varietyShapePrefabs;
 
 
         void Awake()
         {
             persistablePrefabs = new List<PersistableObject>();
             varietyShapePrefabs = new List<ShapeOfPersistableObject>();
         }
         void Update()
         {
             switch (scriptType)
             {
                 case ScriptType.PersistableObject:
                     InputMethodForPersistableObject();
                     break;
                 case ScriptType.ShapeVariety:
                     InputMethodForObjectsVariety();
                     break;
                 default:
                     break;
             }
 
         }
         #region object
         private void InputMethodForPersistableObject()
         {
             if (Input.GetKeyDown(createKey))
             {
                 CreateObject();
             }
             else if (Input.GetKeyDown(newGameKey))
             {
                 BeginNewGameForObject();
             }
             else if (Input.GetKeyDown(saveKey))
             {
                 storage.Save(this);
             }
             else if (Input.GetKeyDown(loadKey))
             {
                 BeginNewGameForObject();
                 storage.Load(this);
             }
         }
 
         void CreateObject()
         {
             PersistableObject instance = Instantiate(persistablePrefab);
             Transform t = instance.transform;
             t.localPosition = Random.insideUnitSphere * 5f;
             t.localRotation = Random.rotation;
             t.localScale = Vector3.one * Random.Range(0.1f, 1f);
             persistablePrefabs.Add(instance);
         }
 
         void BeginNewGameForObject()
         {
             for (int i = 0; i < persistablePrefabs.Count; i++)
             {
                 Destroy(persistablePrefabs[i].gameObject);
             }
             persistablePrefabs.Clear();
         }
         #endregion
 
 
 
         #region Shape
         private void InputMethodForObjectsVariety()
         {
             if (Input.GetKeyDown(createKey))
             {
                 CreateShape();
             }
             else if (Input.GetKeyDown(newGameKey))
             {
                 BeginNewGameForShape();
             }
             else if (Input.GetKeyDown(saveKey))
             {
                 storage.Save(this);
             }
             else if (Input.GetKeyDown(loadKey))
             {
                 BeginNewGameForShape();
                 storage.Load(this);
             }
         }
         void CreateShape()
         {
             ShapeOfPersistableObject instance = shapeFactory.GetRandom();
             Transform t = instance.transform;
             t.localPosition = Random.insideUnitSphere * 5f;
             t.localRotation = Random.rotation;
             t.localScale = Vector3.one * Random.Range(0.1f, 1f);
             varietyShapePrefabs.Add(instance);
         }
 
         void BeginNewGameForShape()
         {
             for (int i = 0; i < varietyShapePrefabs.Count; i++)
             {
                 Destroy(varietyShapePrefabs[i].gameObject);
             }
             varietyShapePrefabs.Clear();
         }
         #endregion
 
 
         public override void Save(GameDataWriter writer)
         {
             switch (scriptType)
             {
                 case ScriptType.PersistableObject:
                     //before save, need to open file via File.Open
                     writer.Write(persistablePrefabs.Count);
                     for (int i = 0; i < persistablePrefabs.Count; i++)
                     {
                         persistablePrefabs[i].Save(writer);
                     }
                     break;
                 case ScriptType.ShapeVariety:
                     //before save, need to open file via File.Open
                     writer.Write(varietyShapePrefabs.Count);
                     for (int i = 0; i < varietyShapePrefabs.Count; i++)
                     {
                         varietyShapePrefabs[i].Save(writer);
                     }
                     break;
                 default:
                     break;
             }
 
         }
 
 
         public override void Load(GameDataReader reader)
         {
             int count = reader.ReadInt();
             switch (scriptType)
             {
 
                 case ScriptType.PersistableObject:
                     for (int i = 0; i < count; i++)
                     {
                         //PersistableObject @object = Instantiate(persistablePrefab);
                         PersistableObject instance = shapeFactory.Get(0);
                         instance.Load(reader);
                         persistablePrefabs.Add(instance);
                     }
                     break;
                 case ScriptType.ShapeVariety:
 
                     for (int i = 0; i < count; i++)
                     {
                         //PersistableObject @object = Instantiate(persistablePrefab);
                         ShapeOfPersistableObject instance = shapeFactory.Get(0);
                         instance.Load(reader);
                         varietyShapePrefabs.Add(instance);
                     }
                     break;
                 default:
                     break;
             }
         }
     }

Please help me to figure out. thank you