After updating to Minecraft 1.17.1 it failed to launch and I recieved this error;

Failed to download file.
Name: 21w11a.jar
URL: https://launcher.mojang.com/v1/objects/07ad8b23e33d195fd897133c9c0e35d7fa1593eb/client.jar
Error details: No network connection available
Filename on disk: 21w11a.jar
Path: C:\Users\James P Lively\AppData\Roaming\.minecraft\versions\21w11a\21w11a.jar
Exists: Nonexistent

then when it did run I got a strange error, then the world loaded but with no physics just fell right through and kept falling., see the Attachtments.

I am not running any current Java version if that helps.

Addendum;
I installed Java and the world loaded, but I still fell through, the when the chunks loaded the skins on my character and the Villagers were blacked out, I started new world and now I am Invisible.