Well that's dumb. The reincarnation serves no purpose at all. They try to act like the MC needed his past live knowledge to make gravity useful, but is it really that hard to understand something as simple as "I can train harder if I make myself heavier" ? Even without knowing what gravity is, this is an easy conclusion to come to by just experimenting and thinking for a minute or two.
Also, I don't see how no one else ever thought of a way to make gravity magic somewhat useful. Making what you touch
heavier ? No one ever thought of a way to make this useful ? Really ?
In any case, I got nothing better to read so whatever.