KeepInventoryX

Note: I've only tested this plugin for version 1.14, but it should work on version 1.9+.

This plugin allows you to customize what players will keep when they die.
It is very lightweight and has no separate configuration file.
Instead, the Plugin is configured through the following permissions:

• keepinventoryx.keep - keep all items (does not include xp)

• keepinventoryx.keeprenamed - only keep renamed items

• keepinventoryx.keepxp - keep all experience points (does not include any items)

So, to get the behavior of the builtin /gamerule keepInventory true,
you would need the permissions keepinventoryx.keep and keepinventoryx.keepxp.

(This plugin is based on https://www.spigotmc.org/resources/keepinventory.1638/ and adds the keepinventoryx.keeprenamed option)