I suspect the style changed due to a change in (maybe coloring/shading) assistants, since it doesn't seem dramatic enough to be a change in artist. I can't read the credits page to be sure tho.
The lifespan thing is simultaneously interesting and weird. But yah, reptiles live friggin foreverrrr. Hope everyone finds their happiness tho, no matter how brief~~
I read the webtoons version, but the typesetting is terrible. Thanks, Luna Lotus for having this version so I can at least read the chapters with a bearable font size, for a little bit.