It's good that the new body isn't overly human.
I just read these first three chapters, but the real joke of the title took a minute of reflection to set in. "Isekai Tensei" sounds incredibly generic, meaning essentially "Otherworld Reincarnation", but in this case, it's the world itself (Earth) that has been reincarnated/remade into a fantasy world. Kinda clever. And now I see from other comments on the series that I misread the title, and that it's "Iseikai Tensei" and uses the kanji for star/planet, usually read as "hoshi", but read as "sei" this time and actually uses that same kanji in "tensei". Even more clever.
Curious if the mother uploaded her brain to a machine or if she actually died in the intervening 50k years. Logistically, altering her form into something long lived makes more sense if she wants to guide the remade world into something viable, but even if she did, that doesn't necessarily mean there's anything left now.