The placement in the season may not be ideal, but it can't be denied that this episode is not only not filler, but an essential addition to Primal.
The show is known for its brutal violence, but this is not just for some sick pleasure in bloodshed. It is an elaboration of the naturalistic perspective (hence Darwin being the deliverer of the theory). Within the context of the show, the violence involved does not speak to the moral debauchery of the characters but rather to the necessary capacity for violence in a brutal environment.
Obviously, these ideas can be understood from other episodes, but concretely putting them into words here opens up a nice pathway forward if Genndy decides to go with his anthology idea for this series. It's not just about Dino and Caveman beating prehistoric monsters' skulls in, it's about being Primal.
Aside from all that, it's just a very well-written and entertaining episode. I think the art style fits the modern era particularly well, dare I say better than the prehistoric setting. I'm glad to see the rating trending upward.