“Jurassic World: Rebirth,” featuring Jonathan Bailey and Scarlett Johansson, is mediocre yet still thrilling. (photo courtesy of Universal Pictures)

Between a zombie horror flick and dino thriller, the nemeses in each should be simple: fast-running zombies and the beasts that once reigned supreme. Not so. Sequels must build and build and build. The lore, the expanded universe, now reigns.

For “Jurassic World: Rebirth,” the seventh film in the franchise must distinguish itself from others with an island populated by hybrid dinosaurs. No raptors here, but how about raptors with wings? Or maybe some hideous creature that looks more suited for a showdown with Kong?

Zombies haven’t changed much, have they? Whelp, in “Years,” we’ve got runners, obese crawlers and near invincible alphas that lead hordes and enjoy removing heads. Two simple premises enter the new presidency with much more grandiose expanded worlds, but they attempt to tell more focused stories.

This is homework cinema. Each film requires a degree of franchise literacy. In 2002’s “28 Days Later,” a study on the chemical causes of aggression creates the rage virus that spreads to people. By the end of “Weeks,” the infected escaped England. Almost three decades later, the virus has been pushed back to the U.K., where its inhabitants are quarantined indefinitely.

“Rebirth” heads to a different kind of quarantined locale, but oh boy, did that franchise take some turns since its 1993 debut. Eventually, dinos ended up roaming the planet, changing society forever. Not really. Now, these prehistoric creatures both cannot survive in most climates and, even worse, no longer hold public interest. Nobody cares about them anymore.

Apparently, the original R&D team (and the latest filmmakers, too) predicted this and began splicing DNA, creating some horrifying, unsightly monstrosities that also contain genetic anomalies desired by Big Pharma. So a crew journeys to a forbidden kingdom in search of a miracle cure.

Back in “Years,” a small community thrives in isolation from the mainland. But a young boy must venture out with his father as a rite of passage. First, he’ll learn about the infected. Next, he’ll uncover truths his guardians seek to keep from him.

Now comes a point of divergence. “Rebirth” relies on standard fare that continues to fail this franchise, like annoying people making dumb choices. Scarlett Johansson leads a cast of familiar faces in a film designed as a return to form. That all sounds fine. If only the CliffsNotes panned out on screen.

Terrible choices abound. In one cringeworthy sequence, a civilian caught in the mayhem loudly drags an inflatable raft in front of a T-Rex. Compare what doesn’t work in “Rebirth” to what shouldn’t work in “28 Years Later” – yet it does.

“Years” markets Aaron Taylor-Johnson, Jodie Comer and Ralph Fiennes as top billing, but they aren’t the lead. That honor belongs to young Alfie Williams as young Spike. He navigates frustrations with a less-than-honorable father and a mother who needs a doctor.

Thanks to director Danny Boyle and writer Alex Garland, who also teamed for the original film, this sequel is thrilling, stylistic and emotionally rich.

“Rebirth” sure tries to present characters of worth, but every single heartfelt moment is obnoxious. Director Gareth Edwards seemed to be on a hot streak with “Monsters,” “Godzilla” and then “Rogue One,” but “Rebirth” marks his second watchable but bland contribution. But perhaps bland is what folks need.

To be honest, “28 Years Later” won’t appeal to broad audiences. The original might’ve set up the zombie trend to come, but trailblazing is a thankless job. Running zombies were a “sin” at the time. This contribution stylistically builds on the original in exciting ways, though the last five minutes might turn off a lotta folks.

As for “Jurassic World: Rebirth,” it’ll remind folks that there’s still life in this film series. But it’s also a reminder of how good these films have been and could be again. Alas, considering how well it’s doing right now at the box office, expect more of the mind-numbing, mediocre same.

So even though “28 Years Later” should win, “Rebirth” has more fans. Meaning we all lose.

Jamie (Aaron Taylor-Johnson) and his son Spike (Alfie Williams) make “28 Years Later” thrilling, stylistic and emotionally rich. (photo courtesy of Sony Pictures)