It is not clear. Ask your DM.
The characteristic of the favorite enemy of the ranger says:
Choose a favorite type of enemy: (…) you can select two humanoid races
(how gnolls Y orcs)
No example of race is present within the Player manual, but both are present in the Dungeon Master's Guide and the Monster Manual. And the half races are only present in the Player manual.
Which seems to suggest that the careers of players should not be considered. (Then there are no half races).
This presents 4 possibilities:
- half races are included in humans
- half races are included in their non-human lineage
- Half races are included in both lineages
- half races are not included at all
Personally, I would say that they be included in your non-human lineage (therefore, half elf with elf and half orc with orc), due to their statistics blocks (scores, size, speed, etc.), since their blocks are tilted more towards the nonhuman than the human.
Also, if you choose to use races from both monster lists and playable races, there are conflicts.
For example, in playable races (of the Dungeon Master's Guide), races such as Goblins and Hobgoblins are listed separately; but in the Monster Manual, all are listed under the Goblinoid race.
If you choose to only use the Dungeon Master's Guide Y Player manual races, end up being multiple omissions. (Gith, Quaggoth, Sahuagin, Changers, Thri-Keen, Yuan-Ti)
If you choose to use only races with monster statistics blocks, such as Monster Manual, there are still omissions. (Dragonborn, Half-Elf, Half-Orc, Tiefling) (not counting the modules and subsequent books).
So it seems that there is no easy answer, because there is always something in conflict without DM intervention.