I think I agree with the guys. What they are saying is that your tank, likely, was not cycled to the point that it could handle the bio load you placed on it (abruptly?). Ammonia and nitrites in the water = no appetite.
Normal cycling times are 3-5 weeks. With seeding, you are right, it can be faster but you need to make sure you feed the bacteria well. Your wordage "used shrimp to kinda jump start the ammonia cycle" makes me think you only "kinda" started your nitrogen cycle. Hence, the outcome.
2 ppm ammonia is far from lethal dose, enough for fish to lose appetite and be quite stressed but should not kill right away. Perhaps your nitrites are high too - must check those.
7.6 pH is fine, I'd agree. Not a big deal at all. If it was over 8, then I'd try to lower a bit.