EXCEL Capture the value of a cell before change

My objective:
In order to archive the previous content of a cell before a change, I created a macro. However, when multiple cells are selected, I encounter problems. The macro seems to stop working.

(for your information, in the case of multiple selection, I do not wish to archive the values; I just want to display a message)

The Workbook:
I have created two tabs: a "data" tab and a "config" tab.
In the "config" tab, I named a cell "end_of_list" to point to the storage location for the archives.

Here is the macro for Sheet 1 (data):

'***********************************************************
' Declaration of public variables
'***********************************************************
Public selected_cell_value As String
Public history_content As String
'
'
'***********************************************************
' Macro triggered after a change in the content of a cell
'***********************************************************
Private Sub Worksheet_Change(ByVal Target As Range)
' Disabling event-triggered macros to make the
' modification without interfering with Private Sub Worksheet_Change
Application.EnableEvents = False
' Inserting a cell at the bottom of the list
storage_address_previous_value = Application.Range("end_of_list").Address
Application.Range("end_of_list").Insert Shift:=xlDown, CopyOrigin:=xlFormatFromLeftOrAbove
' Archiving the value in the "config" tab
Sheets("config").Range(storage_address_previous_value).Value = history_content
' Reactivating event-triggered macros
Application.EnableEvents = True
End Sub
'
'
'*********************************************************
' Macro triggered after selecting a new cell
'*********************************************************
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
' Storing the value contained in the newly selected cell
' This action allows to memorize the content
' of a cell before making a value change
On Error GoTo sub_macro_01
' The content is stored in the public variable
' "selected_cell_value"
selected_cell_value = Range(Target.Address).Value
history_content = "Tab " & ActiveSheet.Name & " " & Target.Address & " : " & selected_cell_value
GoTo sub_macro_02
'---------------------------------------------------------------
' Subroutine for handling errors and multiple selections
sub_macro_01:
' An error message is stored in the public variable
' "selected_cell_value"
history_content = "Error or multiple cell selection"
' End of the subroutine
'---------------------------------------------------------------
sub_macro_02:
End Sub
'
'
Sub unblock()
'**********************************************************
' Macro to reactivate event-triggered macros
' in case of failure
'**********************************************************
Application.EnableEvents = True
End Sub

'
'
And in ThisWorkBook:

'**********************************************************
' Initialization macro
'**********************************************************
' Upon opening the workbook, cell A1 of the
' "data" sheet is selected. The goal is to capture
' the current value of each newly selected cell
' This value is stored in the public variable
' "selected_cell_value"

Private Sub Workbook_Open()
Application.EnableEvents = False
Sheets("data").Select
Range("A1").Select
Application.EnableEvents = True
End Sub

Thank you in advance to anyone who can spare a little time for me