Why haven't apple made a latest update for the ipad1? I bought this iPad for my children and I can't download Netflix on it as it needs ios6 or newer update?

Because its hardware is too old to handle iOS 6.

(100484)

These are user-to-user forums, you're not talking to iTunes Support nor Apple. But as Niel says it's unlikely to happen as to doesn't have the ram or processor to support iOS 6.

Have you checked to see if the developers of the Netflix app have an older compatible version of their app in your country's app store ? Try downloading the current version on your computer's iTunes so that the app is in your purchase history, and then on your iPad go to the Purchased tab in the App Store app and see if you can download an older compatible version of it.