Let’s review the role of a comma in a list.
When you list things in a sentence, use a comma between every item in the list including before the final conjunction that joins the last two items.
It used to be, when I was a child, that no comma was placed before the final conjunction, however the rule has changed. It is now common place and taught to put the comma there. This is called the Oxford Comma and should be taught as a punctuation rule.