A single person did not make up sign language. It is not an alternative to language, but rather there are many sign languages each of which is constantly changing based on the needs of the people who speak it. American Sign Language is most closely related to French Sign Language, and the two share common roots.
Yes, the word 'sign language' is a noun, a compound noun, a noun made up of two words that form a noun with a meaning of its own.
In British Sign Language (BSL), the sign for "yes" is made by moving your fist up and down in a nodding motion.
first you put up your pointer\index finger and curl it down a little and you have made an a good job
In American Sign Language, the sign for "can't" is made by forming both hands into fists with thumbs sticking up, then placing one fist on top of the other and moving them down and outward.
In American Sign Language, you can sign "suck it up" by signing the fingerspelled letters "s-i-u" followed by a sign for "deal with it" or "handle it."
In American Sign Language, the sign for 'douche' is made by forming an 'A' handshape with your fingers and turning it so that it faces downward toward your body, then moving your hand up and down a couple of times near your shoulder.
In American Sign Language, the sign for "wild cat" is made by signing WILD and then CAT.
In American Sign Language, the sign for "love" is made by crossing arms over the chest and hugging yourself.
Of course, sign language is not said in spoken words (although some deaf people do speak, and do read lips). Sign language uses symbolic gestures made with the hands; it is a complete language, with its own grammar, idioms, etc. I enclose a link to how to sign the word "funny."
This is for American Sign Language. I do not know sign in any other language Make a fist with one hand and point your thumb up. Grab your thumb with your other hand. Pull your thumb out of your hand that's grabbing it.
In American Sign Language, the sign for "two thumbs up" is made by extending both thumbs upward, with the rest of the fingers closed against the palm of the hand. This gesture is often used to convey a positive or affirmative message in informal settings.
up and down