Splitting a column value (by ',') and creating a new table with column headers

Question

I'm relatively new to SQL here. In SQL, I'm trying to convert an existing table into a new table where two columns are split into rows (by a comma ',').

Stack Overflow has recommended a similar solution here, however more complex as I don't require trimming/or replacing characters.

Original table

Row Index	Question Titles	Answers
0	Colour, Registration, Make, Model	Red, A123456, Ford, Fiesta
1	Colour, Registration, Make, Model	Blue, B23456, Audi, A3
2	Colour, Registration, Make, Model	Purple, D52625, Nissan, Skyline
3	Colour, Registration, Make, Model	Orange, Y336363, Toyota, Supra

Desired outcome

Row Index	Question Titles	Answers
0	Colour	Red
0	Registration	A123456
0	Make	Ford
0	Model	Fiesta
1	Colour	Blue
1	Registration	B23456
1	Make	Audi
1	Model	A3
2...etc	Colour	Purple

This is what I have so far, but I'm struggling to incorporate the 'Answers' side:

DECLARE @Get_Question_Titles VARCHAR(4000);
DECLARE @MaxID INT;
DECLARE @ThisID INT;

SET @Get_Question_Titles = (SELECT TOP 1 Question_Titles FROM Test_Car_Table)
--Get the max Row_Index (for the While loop)
SET @MaxID = (SELECT MAX(Row_Index) FROM Test_Car_Table)  
SET @ThisID = 0

DECLARE @Main_Table TABLE (ID INT, Title varchar(MAX), Answer varchar(MAX))

WHILE @ThisID <= @MaxID
BEGIN
    --Split the Get_Question_Titles up and insert into @Main_Table
    INSERT INTO @Main_Table
    SELECT @ThisID AS Row_Index, VALUE AS Question_Titles, NULL AS Answer
    FROM STRING_SPLIT(@Get_Question_Titles, ',')

    -- ADD VALUES TO COLUMN

    --Increment @ThisID
    SET @ThisID = @ThisID + 1
END

SELECT * FROM @Main_Table

This produces the following:

Row Index	Question Titles	Answers
0	Colour	NULL
0	Registration	NULL
0	Make	NULL
0	Model	NULL
1	Colour	NULL
1	Registration	NULL
1	Make	NULL
1	Model	NULL
2...etc	Colour	NULL

Does anybody know a way to produce the desired outcome?