Neutral is not ground. Neutral carries normal operating current. Ground is just a safety shield, and can't carry current if it's to do its job. Back at the service panel is a neutral-ground equipotential bond meant to keep all the conductors near ground (not floating at 4000V due to a transformer leak), and to provide a return path for fault current. Failure to understand this bond leads many to believe neutral and ground are interchangeable. Not so.
Bringing lazy to a whole new level
This is a metal conduit wiring method, where the metal pipe carries the ground for you. Easy peasy, ground is done! But this person was so lazy they couldn’t even be bothered bringing a (or a proper color) neutral wire.
Just throw a neutral wire in the pipe
Since it's conduit, it's easy to add wires. Pull a real neutral wire into that pipe (or if separate circuits, 1 neutral per circuit; remember gray is a legal neutral color, my roll of grey wire is my favorite one!) Wire it properly then remove that jumper.
Noting that in a multi-wire branch circuit (MWBC), it is normal for 2 hots to share 1 neutral. Since this setup has no neutrals at all, you get to decide which is an MWBC. Make sure to follow the MWBC rules.
And you'll probably need to do this on every recep, lamp, disposal, dryer, range, and every other 120V load on the premises.
... And test
Lastly, check out each of your circuits by plugging small loads (night lights, etc.) into each circuit, and installing a GFCI breaker on one circuit at a time. You need to have > 10ma (1.2 watt) load on each circuit so you can detect crossed neutrals.
For MWBCs and 240V loads, you can use a 1-pole GFCI breaker and simply land both hots on the breaker hot screw. Temporarily, for testing; it MUST be undone right after testing, especially on MWBCs.
Or, you can use a 2-pole GFCI breaker, and when testing 120V circuits simply leave one hot screw unused. That will let you fully test 240V and MWBC circuits.