The problem of low hit points on humans

[Turin]

For the people who can´t accept a bit higher hp for heros:

Consider this:
a run of the mill human unit has 10 hp.

The most skilled recruitable human fighters already have 15+hp(Emerald Lord,Warrior Chiefs, Boar Lord etc). So clearly skilled fighters can gain more than the ordinary amount of hps. Why does it break immersion then if Hero units, i. e. the best of the best have ~20 hp?
After all it would be only the logical progression from
standard soldier---->elite soldier---->Hero