CRJ-200 First Officer reported during an inflight shut down of an engine for low oil pressure indication; checklists were not followed; resulting in the thrust reversers not being armed for landing.

Narrative

About half way through our flight from ZZZ-ZZZ1 we received a low oil pressure warning message that was intermittent. Following the QRH we confirmed and brought the affected thrust lever back to idle and the message went away. The QRH at that point directed us to monitor and we continued. In our descent the message came back while at idle and did not go away. Following the QRH again; the oil pressure was indicating low oscillating between 23-39 PSI and the oil temperature was abnormally low in parameters with the QRH directing us to shut the left engine down. We advised ATC and preformed the engine shutdown. Everything through the rest of the descent and approach was done to SOP however; we did realize that being task saturated we did make the mistake of not running the landing checklist and forgetting to arm the operating engines thrust reverser. The landing was completed and we taxied off the Runway XXR. We asked Fire Rescue to come check the planes left engine to be safe then continued our taxi in.The event occurred due to low oil pressure. I believe the complexity was increased due to the message going away and coming back so many times. When the messaged remained on we followed the QRH and shut the engine down just prior to turning downwind. This caused us to run multiple checklists later than we normally would; further increasing task saturation and complexity which led to the thrust reversers being forgotten/checklist being missed.