Not quite. There were sections of the charter that expressly related to noble rights, but there were also sections that related to the rights of all 'free men'. Now, in 1215, most of the population was still in various of servitude (serfdom, etc), so it certainly didn't apply to anywhere near everyone, only a fairly privileged minority, but it was still a lot broader than just nobles. And over the centuries, the number of men who were 'free men' increased more and more and the rights granted by Magna Carta became more and more widely available.
“And over the centuries, the number of men who were ‘free men’ increased more and more and the rights granted by Magna Carta became more and more widely available. “
Thank you for that. It adds perspective, which I sorely lack from my vantage.