unknown island most likely has no signal.
Aircraft would have an ELT beacon sounding off. Eventually help may or may not come. Last known radar contact and flight plan will direct SAR efforts.
The most important part of survival is shelter, then water, than food, in that order.
Build a shelter, build a fire, then go get the food. Us the box the food was in to build a rain/dew trap for more water. Go hunting. Dig in.