It has been ages since I've read the books but... yeah, muggles in the Harry Potter setting are completely incapable of fighting back if the magicals decide to fight. It goes into the Jackie Chan Adventures of 'Magic can only defeat Magic!' thought process.
Which makes absolutely no sense. Because they're as human as anyone. And for every one Tom Riddle and Harry Potter you have a hundred average Joe's and Jane's who can barely perform basic Shield spells. Hence why the Weasleys enchanted clothing was so popular.