The United States Declaration of Independence contains one of the most well known and enduring lines in English:
We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.
and was paraphrased by Michelle Obama in her speech at the Democratic National Convention:
"All are created equal."
The Massachusetts Constitution contains
All men are born free and equal...
and The Virginia Declaration of Rights contains
... all men are by nature equally free and independent ...
While I understand the Declaration of Independence to mean
All equally have the same rights
Would it not have been more grammatically correct to use the adverb
All are created equally
I realise that
All are equally created
may have a different meaning.