"Steven on the other hand was created by mixing human and gem DNA so he’s a completely new kind of being. He is the only gem to be born thru biological reproductive means(Rose shapeshifted a womb for him to be born from)." Ian JQ
He is more than just a regeneration of Rose if you mean the way gems regenerate new forms from thier gems since he came out of a womb like a human baby. His human side also made him resistant to the technology used to destablize gem forms.
Agreed that Rose could still be herself hidden away inside Steven/ her gem. I'd like to see her reappear but only briefly to keep the tragic trade off dynamic.