You're describing a something like say a Sorceror vs Wizard in DnD terms.
Gifted or inherited magic vs magic calculated via pure intellect and study.
MC is very clearly the latter.
Not early 2000s. First iPhone, the first "casual" smartphone, was in 2007. You'd maybe wait until 2009 for when people began using it regularly as a video recorder, if that. In a pre 4G world data slower and lower capacity. Recording via a phone and later uploading it was rather frivolous.
May...
Dunno if it's the author or mangaka, probably the latter.
This manga has a critical flaw with god awful pacing. It's as if he/she is only drawing the highlights of the plot, rather than any meat. There's near zero context on what's going on.
Unfollowing this. Either the mangaka or the writer has terrible pacing. I am inclined to believe it is the former.
The gigantic holes between events is just too gaping for it to be the author. It's like the mangaka is only interested in drawing the highlights and there's no context/preparation...