I assumed their baby was a girl, you know like for a typical romance webtoon, their child ...

Yep it’s a little boy, unless that part changed from the OG plot. I mean even the body the MC occupies is not the original Elisha since she died in childhood. But I think this stayed the same since the baby looks more like his dad and has him mom’s eyes. He’ll be more powerful then his original self since he’ll have he may have his mom’s holy water powers and dad’s wind.