iOS update

New to Apple. Bought an older ipad from someone and it has IOS 9.3.5 and when I search for updates, it says it has the latest version which I know is not the case. Is it because the ipad won't support but a certain IOS? Is this Apple's way of keeping you buying? It won't let me install Kindle or Messenger or Facebook from the App Store. I get message that it is not compatible with this ipad. iPad 2 - Model MC979LL/A