The three laws of relativity unmodified until the twentieth century when John Rambo added the law of special relativity - “when you’re pushed, killing is as easy as breathing”.

It never ceases to amaze me how difficult it is to come up with something worthwhile and original (pedants, no need to point out inspiration or standing on the shoulders of giants) without years of work. Art, science, music, whatever. Yeah, there are lucky one-offs, but even something as simple sounding as “For every action, there is an equal and opposite reaction” distills the semi-intuitive into something concrete and explainable.

He did not come up with the principle of inertia, it was already employed.

Also, it's not just people that punch you back, things punch you back too.

He also seems to have figured out modern fashion, amazing!

Hey, he also figured out that things that are moving usually move some more

Hey, that's unfair. He also figured out that if things push at each other, they get pushed.

While it seems obvious on an intuitive level, it is actually an important observation that can't be taken for granted! :)

or moves at constant speed

That guy Newton didn't even know that inertial frames of reference weren't absolute.