The Predator featured in 'Prey' is a somewhat primitive example of its species compared to the Predators featured in the original films. This example of the creature relies more on brute force and hand-to-hand combat when engaging its prey rather than the stealth-based attacks of its later kin.
Its technology and weaponry reflect this approach. It eschews plasma-based projectiles in favour of metal spear tips and arrows, and its face mask is of a more bone-like material rather than the smooth steel of later examples of its species. The mask functions identically to the ones worn by the later visitors to Earth.
While cosmetically different than the other members of the Yautja, its origin being from a different hemisphere on the Predator homeworld, it still adheres to the established honor code; it spares those it doesn't deem a threat.
The prequel implies that this is the first member of its species to have hunted on Earth. This is why it looks the way it does as it's a lesser evolved Yautja.
Happily it looks like they've ditched the god-awful AVP timeline too which showed Plasma canons etc being used thousands of years ago.