if i have a jack and a sally in play and then a simba Lv.3 or 4 is play, can jack and sally go the discard pile together and then sally activates letting me pick the same jack sent with her for her effect?

they end up in the grave at the same time and then sally activates after the fact in my opinion...letter her effect target him.

her effect activates as she is discarded, as you said they are both discarded at the same time meaning she cannot pull the jack that has just died. The effect hits just before she hits the discard pile. Since neither she or jack has technically hits the pile yet, that jack cannot be pulled.