My headcanon theory is indeed that English is a creole language.
Mix the grammar, verbes and functional words of the lower-status people (natives, imported slaves) and nouns of the higher-status people (invaders, colonizers and masters) and boom, after a few generations you get a creole language.
This theory works surprisingly as well for English as for, for example, Caribbean creoles.
Sometimes boss is self. Sometimes boss is man. Sometimes boss is rock who thinks with lightning.