i'm really confused what is thr purposes of the alternative coins and how this will be invented? and what are the good benefits of this alternatuve coins? 
Some altcoins are created for experimental purpose, to see how people react if this kind of innovation is implemented. They created by cloning or forking chain thru modifying the codes, some starts from scratch but have the other early coins source code as reference.
One of the obvious benefits of alternative coin is experiencing the transaction in more cheaper way and at the same time, it helps promotes bitcoin to people.