The low presence of ammonia and presence of nitrite (non-toxic) shows that chemically your tank is non-toxic. The Nitrate reading will likely fall in 1-2 days as its a false positive from the Nitrite which is cross read by Nitrate test kit. As Nitrates rise again, a water change can level you back to good levels (about 5 ppm)
I would remove about a half gallon of salt water and replace it with RODI to dilute salinity. Remove the shrimp and start shopping for your clean up crew. Congrats, you are cycled!