Run a line of hoppers from under the first chest to almost under the second, finish the line with a dropper facing up into the second chest. Since you have a chain of hoppers, only one item will be in the dropper at a time. Set it up with a comparator sending a signal back to itself to put the item into the second chest.
What is the most simplistic way?
Edit: The chests are like 10 blocks apart.
Run a line of hoppers from under the first chest to almost under the second, finish the line with a dropper facing up into the second chest. Since you have a chain of hoppers, only one item will be in the dropper at a time. Set it up with a comparator sending a signal back to itself to put the item into the second chest.
I'm curious, though, why no rail?
https://m.youtube.com/channel/UC2tQ9HEChml_-dNSuKIA2gw
The simplest way? Carry it over in your inventory and then stuff it in the other chest.
Yeti covered the simplest automatic way (without using minecarts).
U can use water streams