Following up from my earlier comment, I can now open Minecraft with no issues if I run the latest beta of the Minecraft Launcher as an administrator, as stated by 2007IGN.
Updated to beta version of the Launcher (b.2.3.592-1.1.128) and I am still experiencing the issue.
Failed to download file.
Name: ancestry.ogg
URL: https://resources.download.minecraft.net/86/868c7a7c4d9358d631fa2f9abfc6bbf05d88292d
Error details: transfer closed with 1409843 bytes remaining to read
Filename on disk: 868c7a7c4d9358d631fa2f9abfc6bbf05d88292d
Path: C:\Users\<username>\AppData\Roaming\.minecraft\assets\objects\86\868c7a7c4d9358d631fa2f9abfc6bbf05d88292d
Exists: Nonexistent
The workaround listed above does work still, but, obviously, that's not ideal.
Tested in 1.20.40.20 Preview.
The walking sounds of the Wither Skeleton are still the same as the regular Skeleton. The sound played when the player hits a Wither Skeleton and the sound played when a Wither Skeleton drops from a high block are correct. I've looked through other MCPE cases recently and I didn't see one related to the walking sound, so I'm uncertain whether this issue can be tied to this case. For vanilla parity, it would be nice if all Wither Skeleton sounds in Bedrock matched Java.