It turns out, they were the main characters.

Mu Zhian transmigrated to a fantasy world and became a supporting character destined to be used as a stepping stone by the protagonist.
Mu Zhian had intended to befriend the protagonists, those chosen ones, but upon turning around, he discovered that the girls surrounding him were either the protagonists' childhood sweethearts or their fiancées.
The most baffling thing is that all the girls who should have liked the protagonist ended up falling for Mu Zhi'an, a supporting character. Surrounded by these stunningly beautiful girls, Mu Zhi'an hatched a daring plan: to eliminate the protagonist and seize power. After finally managing to defeat several protagonists and gain a large amount of resources...