Original artwork, not a still
Actually, I've always had a rather extensive vocabulary, not to mention a phenomenal grasp of grammar and a superlative command of syntax. I simply chose not to employ them.
Behind the line
What it means
Our interpretation.
The speaker claims to have long possessed a wide vocabulary, superb grammar and masterly syntax, then adds that they simply decided not to use any of it. The pompous list of talents sets up a dry, self-mocking flourish, presenting inarticulacy as a deliberate choice rather than a limit.
Context reviewed