Wikipedia states:
The terms "id", "ego", and "super-ego" are not Freud's own. They are latinisations by his translator James Strachey. Freud himself wrote of "das Es",[5] "das Ich",[19] and "das Über-Ich"[28]—respectively, "the It", "the I", and "the Over-I" (or "I above"); thus to the German reader, Freud's original terms are more or less self-explanatory. [...]
What's the referent of the German pronoun 'Es'?
Why didn't Freud name (the concept known as ⟨Es⟩) with the referent itself instead? I.e., wouldn't naming ⟨Es⟩ as 'Instinkt' to mean 'instinctual drive' make the term easier to understand and more self-explanatory?