What do these mysterious logs mean on my Apple device?

Those logs are totally normal iOS analytics files. JetsamEvent means the system force-closed an app because it was using too much memory, not a crash or anything malicious. LowBatteryLog is exactly what it sounds like, iOS recording battery level and power behavior. The mediaplaybackd ones are just media services doing background stuff like audio or video handling.

Apple collects these for diagnostics and they show up more often on new phones, after updates, or when battery life is being weird. They look scary because they’re raw system data, but they don’t mean your phone is hacked or broken. Pretty much every iPhone has a list like this if you dig into analytics.