Learn English – Why are nicknames called “nicknames”

Hit Points as a way of referencing the general remaining health of a person is taken from the game Dungeons and Dragons, originally published back in the '70s. It was the first really popular stat-based role-playing game, and became kind of a touchstone for geekyness.

The idea was that you had a given number of hit points, based on your character class, constitution, and level. When attacked, you lose a certain number based on the power of the attack and a die roll. When/if your "HP" drops to 0, you die.

There are other games that use a "hit point" system these days, and probably were before D&D, but that is the game that popularized the concept. If you hear someone talking about "hit points" in real life, they are making a nerdy D&D reference.

I don't think the Angles landed in the British Isles and said:

"Let's call our language Ænglisc now that we moved to this new land!"

Before they migrated, and that took many years, their homeland was already called Englaland or even Engla and they already named their Germanic language Englisc. The only difference is that this place was Angeln in the south-east part of Schleswig, in present-day Germany.

So to answer your question, the word English was used before England was called England but at that time the word England (or its ancestor) already existed. It was just used to designate a completely different place.

As for the English people the Angles themselves were collectively referred to as Engelcynn (as in kin) or Engelfolc (as in folk, German volk).