Single pole switch still controlling multiple lights
It sounds like you swapped your hot and load on the first switch pigtailing the wrong one because when it is off everything else is off.
So your incoming hot should be on 1 side of the first switch that hot should jump to each of the other switches. If everything works correctly when switch one is on you have to figure out the mixed up wires , lucky thing you won’t hurt things by trying different combinations with them all on the same breaker or circuit.