Why are the Xbox 360 editions not playable?

Because they are not backwards compatible

There are separate Xbox One ports of the games that are available

Tere was never a guarantee of titles moving forward.

The standard edition will be playable on the 17th.

Only the elite trooper edition is playable on the 14th

Same problem, system is up to date/connected to xbox live. I have Red dead redemption game of the year edition "plays on xbox one & xbox 360" both of the disks have the same message "This game isn't playable here. for a list of xbox 360 games playable on
xbox one go to xbox.com/backcompat. (0x8082000c). Have no clue how to fix this spent my whole weekend trying to do it please help.

This question may seem redundant, but are you trying to install the game on the Xbox 360 right? The reason for this being is often times people get a little confused as to why Minecraft has so many versions for example on Xbox alone there are three different
versions: Xbox 360 (only downloadable and playable on the Xbox 360), the Xbox One Edition (a port of the Xbox 360 edition), and the Windows 10 edition now commonly referred to as Minecraft Bedrock or just simply "Minecraft."

If you're on the Xbox 360 and it is making you pay for the game, even though you're under the impression you bought the game a few years ago, the likely scenario is that the game wasn't purchased under your account on that console. Since you mentioned having
a sibling, the chances are the game could be downloaded through their account. You need to be logged into the account that purchased the game. Purchase history can be found at http://account.microsoft.com/billing/orders

It's far more likely that a windows 8 xbox edition will exist than 360 games will be playable on pc. I don't see how microsoft can create a 360 emulator without massive overhead and make it run on anything but the best, high end gaming pc's.