Beside the 3 Main Female characters, Rione, Lyudmilla and Telomea, the other harem members are

Elysia, the Hero Descendant, which beside being in the typical hero journey, she is in a journey looking for someone to train and take as a Husband for descendants, in which she find Cross, our MC, Elysia is a glutton, deadpan and airhead character, she train Cross a few times, most of her time, is used as an admiration point for Cross, until LN Volume 4 where she goes on the attack and declare to our main girls that she is going to take Cross as her husband

The Childhood Friend, Giselle, she start as your typical bully to our MC, because he is weak, jobless, level 0, but inside she is a tsundere, after her first duel with Cross, she stopped sort of stop bullying him and turned into rivalry, she start to open up a bit and act as a tsundere, after the big monster fight at the end of Volume 1, she is the permanent partner of Cross from that point, the character that spend the most time with him, and the one that would probably have the most chances to get with him, if it wasn't because she is a tsundere and a childhood friend

Sylphy, a young girl he meet in Volume 4, and another permanent addition as Cross companion, she is a really straighforward character that fall in love at first sight with MC, she is alot of trouble for our MC because, there is a few big bad guys that after her, she is really well liked by the Main Trio and they really open up to her, unlike Giselle or Elysia

Because of a cheat skill, this skill manifest when he got to a near death state at the start of the novel after trying to do a heroic act in saving Elysia from a monster attack, he receive a second chance but is not reflected in his stats window, this ability get explained an explored upon at Volume 4, which carry alot of problems for him, but really easy to get what it do early

What this do, is that he get increased skill speed growth and make him being able to learn any skill without a class restriction (a jack of all trades), but he still can't level up neither gain base stats naturally, so he remain Jobless, at level 0 and 0 base stats

While he is being trained, he get passive skills, like increased defense, increased strenght, magic, etc and these growth incredibly fast and add up to his base 0 stats, which make him super broken, and thats when hardwork come into play, he have to put himself in danger so these skills can level up and he can learn new ones, he can learn skills on the fly and these skills level up in combat, from passives to magic / weapon skills