• My world doesn't have cheats
•  I enabled keep inventory when creating my world 
• To test my keep inventory, I finished fishing and drowned myself. My mule was next to my fishing pond and house.
• I respawned in my house, looked outside, and couldn't see my mule. I don't think it could've gotten anywhere so fast, as I had just died and figured it was a visual glitch. I saved, quitted, then reloaded my world.
• It still wasn't there. If it had died, there wasn't any of the items it had in it's inventory on the floor.
• I had my travelling gear on my mule  has anyone got any explanation?
• [My version is actually in 1.16.4? I don't know why I can only pick 1.16.5]

Edit: https://drive.google.com/file/d/1bemppnniFptc9qMCaaKg2Y1WP5LwqIw7/view?usp=sharing heres the world... i didn't know where else to put the link :]