I'm trying to wire a chandelier and both wires are copper. If I remembered correctly, I was told the wire with the ribbed sheathing would nut to the black (line) #14.
Is this correct?
no; it should go to the white wire.
What would've happened if I had wired this backwards, ribbed to black?
Wired backward increases the chance of shock if one touches the screw base of the lamp while changing lamps. Smaller hands often grip the lamp nearer the base.
Depends on how it is wired. If it is a switchloop where the live is always LIVE, then it would mean the screw base would also always be live and would be a shock risk. If the circuit is wired such the the live goes through a switch and then up to the cwiling, then nothing on the fixture would be live as long as the light is turned off.
Huh? A switch loop should have no bearing on the matter. The grounded conductors should NEVER be switched (except in cases where the switch also opens the non-grounded conductor). If the chandelier has no exposed metal parts that aren't insulated from the wiring, there's really no right or wrong side. If there is such exposed metal (usually the base of the lamp sockets) then that needs to be connected to the grounded conductor.
With single lamp fixtures, the person may not be aware if the switch is on or off while changing the (presumed burned out) lamp. If wired with the hot to the ribbed conductor, the screw shell is hot whenever power is available to the fixture.
The chandelier would have worked normally, the safety would be compromised.