The world of fan perceptions is very different from industry reality.
Fans think that X song or Y song, could not have been performed by anyone else but their faves. But the reality is that composers, songwriters, producers assemble a song from different sources and shop it around to many artists, until someone picks it up and releases it, which might then become a hit.
Examples are,
"Into the new world" was meant for M.I.L.K's second album, they disbanded, so was given to the new group SM was debuting - Girls Generation.
"Love Dive", was offered to Sunmi (among others), but was picked up finally by Starship for IVE, going on to be a hit.
Pretty much 99% of songs produced can be performed by any idol/act.
What other such cases are there, where an iconic song was originally offered or meant for one act, but eventually was released by another to great success?