No. This is beyond ludicrous.
1) The Arc of the Covenant was almost certainly not a Layden jar, because there almost certainly was an electrically conductive pathway between the layers of gold.
2) Layden jars do not have enough capacitance to store a lethal charge of electricity.
3) Ignoring 1) and 2), Layden jars don't magically collect 60KV of charge out of thin air. The ancient Hebrews would need to be doing something to accidentally charge up their ancient supercapacitor, and there's no candidate ritual that would explain that.
To justify point 1):
In the description of the arc, both as cited in Exodus 25:10-22 and Exodus 37:1-9, the Ark is a box of shittim wood (commonly translated acacia) with gold plating on the inside and outside, a golden lid (the "mercy seat"), and four gold rings at the corners to carry it. If the gold plating went all the way up the sides of the box, it would have touched the gold lid, which would have formed an electrical bridge, shorting the capacitor.
In addition, how were the gold rings attached to the Ark? It doesn't say, but
- They had to be attached in a way that would support weight, which eliminates
- Screws were not invented until much later, around 500 B.C.
- Socketing metal around wood requires the metal to be elastic, and gold is not.
Throughout most of ancient period, riveting was the go-to method of fixing metal to wood. Riveting was invented ~3000 B.C. in Egypt, and would have been well understood by slaves fleeing Egypt in ~1500 B.C. (the supposed time of Moses). If the rings were riveted through the wood, those gold rivets would have electrically connected the interior and exterior plates, preventing a charge build-up.
To justify point 2):
According to Wikipedia, a 1 pint Leyden jar has a capacitance of 1nF, and the maximum voltages achieved in the 1700s is estimated at less than 60KV.
The Ark is described as ~1.4 meters long and ~0.7 meters wide and high. That's a bit larger than a pint, but the energy stored is on the surface, not in the volume, so let's generously estimate it at 100nF.
1 Farad is 1 Coulomb per Volt. So at 60KV, a capacitor with a capacitance of 100nF stores 6mC.
1 Coulomb is 1 Amp for 1 second. According to this, the bare minimum of current needed to cause muscular contractions and eventual death is 0.1A. 6mC sustains a bare minimum 0.1A current for only 0.06 seconds, which is not enough time for the muscular contractions to kill you.
So even being generous about the capacitance of an Ark-sized Layden jar, a discharge would not be fatal. You could argue that Uriah had a heart condition and died from the shock of being shocked, but then you could simply argue that Uriah had a heart condition and died from the excitement of touching the Ark.
Which brings us to point 3.
Charging a Leyden jar to 60KV is not something that happens by accident. Early researchers set up contraptions using rotating glass spheres to build the static electricity for the Leyden jars.
The ark is described as an unsealed box with a lid held on by its weight, so any charge inside the box will gradually find its way to the outside, meaning that the Ark would only remain charged in Uriah's time if there was some sort of ritual that happened to keep it charged.
There's simply no specification for such a ritual within the Bible.