British English is not some monolith and was less homogeneous than it even is now at the time many were coming to the Americas. If this were true it would only be true for a particular region. English outside of the UK also diverged as it no longer followed trends happening there, and regional variations went in sometimes different directions.
Even within the US, English isn’t super homogeneous. Look at Appalachian compared to California or someplace. Parts of Louisiana have unique features from Accadian and influence from Spanish.
British English is not some monolith and was less homogeneous than it even is now at the time many were coming to the Americas. If this were true it would only be true for a particular region. English outside of the UK also diverged as it no longer followed trends happening there, and regional variations went in sometimes different directions.
Even within the US, English isn’t super homogeneous. Look at Appalachian compared to California or someplace. Parts of Louisiana have unique features from Accadian and influence from Spanish.