Who had an sketch idea for a parachute around 1495

Leonardo da Vinci

correct, and who is credited as actually inventing it? And what was his intended use for it?

The historian J. Duhem has established that L.S. Lenormand read this passage a century later, was stimulated to make trials, jumping from the tops of trees and buildings, and was quite successful. In 1783, Lenormand gave the invention its name of 'parachute'.
Lenormand told the brothers Joseph and Etienne Montgolfier about it, and the famous pioneering balloonists were then responsible for A'.J. Garnerin's jump from a balloon with a parachute in 1797. This was a direct result of a Westerner having witnessed Chinese parachutes. Needham remarks, aptly: 'There are not many cases in which so clear a line of transmission is detectable.Read more here!

http://library.thinkquest.org/23062/para.html?tqskip1=1&tqtime=1004