Whenever I get killed by any mob, the game crashes. Here are some crash logs from that:
https://crashy.net/AgGPfPtgkm6BHpnX5RVV
https://crashy.net/nTPj0qZw84g8zKCqzEmy
https://crashy.net/XkqGmIzKc3fjdX0rdAkh
https://crashy.net/UQwQ4zDiBqV5FLO0FVBQ

Then, if I try to re-join the world it crashes again. Here is the crash log from that:
https://crashy.net/Gt1XCw0J9MWQjjhcfLX7

If, instead of trying to re-join, I decide to create a new world... my model looks like this:

Something corrupts the pose stack. Any mod can basically cause that. Since the 1.16 release has been out for a long time without anyone having issues like that, it's probably some other mod. Try removing mods till this error goes away.

Stale.