Also a bit glossing over the details if we consider how close Dutch and English are compared with say Slavic languages and English or Latin languages and Englis

Also a bit glossing over the details if we consider how close Dutch and English are compared with say Slavic languages and English or Latin languages and English. I remember reading a while back that Old English and Old Frisian would have been mutually understandable. Although in fairness I doubt most Dutch today would follow a conversation in Frisian.